National Grid (NGG) 20-F 7 Jun 22 2022 FY Annual report (foreign) Financial data

Cover

Cover	12 Months Ended
	Mar. 31, 2022shares
Entity Information [Line Items]
Document Type	20-F
Document Registration Statement	false
Document Annual Report	true
Document Period End Date	Mar. 31, 2022
Current Fiscal Year End Date	--03-31
Document Transition Report	false
Document Shell Company Report	false
Entity File Number	001-14958
Entity Registrant Name	NATIONAL GRID PLC
Entity Incorporation, State or Country Code	X0
Entity Address, Address Line One	1-3 Strand
Entity Address, City or Town	London
Entity Address, Postal Zip Code	WC2N 5EH,
Entity Address, Country	GB
Entity Common Stock, Shares Outstanding (in shares)	3,904,074,348
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Accounting Standard	International Financial Reporting Standards
Entity Shell Company	false
Entity Central Index Key	0001004315
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false
Ordinary shares
Entity Information [Line Items]
Title of 12(b) Security	Ordinary Shares of 12 204/473 pence each
Trading Symbol	NG
Security Exchange Name	NYSE
American Depositary Shares
Entity Information [Line Items]
Title of 12(b) Security	American Depositary Shares, each representing five
Trading Symbol	NGG
Security Exchange Name	NYSE
3.90% Series Preferred Stock
Entity Information [Line Items]
Title of 12(b) Security	3.90% Series
Trading Symbol	NMK PR C
Security Exchange Name	NYSE
3.60% Series Preferred Stock
Entity Information [Line Items]
Title of 12(b) Security	3.60% Series
Trading Symbol	NMK PR B
Security Exchange Name	NYSE
Business Contact
Entity Information [Line Items]
Entity Address, Address Line One	1-3 Strand
Entity Address, City or Town	London
Entity Address, Postal Zip Code	WC2N 5EH
Entity Address, Country	GB
Contact Personnel Name	Justine Campbell
Country Region	44
City Area Code	20
Local Phone Number	7004 3000
Phone Fax Number Description	011 44 20 7004 3004

Audit Information

Audit Information	12 Months Ended
	Mar. 31, 2022
Audit information [Abstract]
Auditor Firm ID	1147
Auditor Name	Deloitte LLP
Auditor Location	London, United Kingdom

Consolidated income statement

Consolidated income statement - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Statement [Line Items]
Revenue	£ 18,449	£ 13,665	[1]	£ 13,360	[2]
Provision for bad and doubtful debts	(167)	(325)	[1]	(234)	[2]
Other operating income (expense)	(13,911)	(10,939)	[1]	(10,847)	[2]
Operating profit	4,371	2,401	[1]	2,279	[3]
Finance income	50	58	[1]	54	[2]
Finance costs	(1,072)	(853)	[1]	(1,020)	[2]
Share of post-tax results of joint ventures and associates	92	58	[1]	87	[2]
Profit before tax	3,441	1,664	[1]	1,400	[2]
Tax	(1,258)	(360)	[1]	(370)	[2]
Profit after tax from continuing operations	2,183	1,304	[4]	1,030	[2]
Profit after tax from discontinued operations	171	337	[4]	235	[2]
Total profit for the year (continuing and discontinued)	2,354	1,641	[1]	1,265	[2]
Attributable to:
Equity shareholders of the parent	2,353	1,640	[1]	1,264	[2]
Non-controlling interests from continuing operations	£ 1	£ 1	[1]	£ 1	[2]
Earnings per share (pence)
Basic earnings per share (continuing) (in GBP pence per share)	£ 0.606	£ 0.370	[1]	£ 0.297	[2]
Diluted earnings per share (continuing) (in GBP pence per share)	0.603	0.368	[1]	0.296	[2]
Basic earnings per share (continuing and discontinued) (in GBP pence per share)	0.654	0.466	[1]	0.365	[2]
Diluted earnings per share (continuing and discontinued) (in GBP pence per share)	£ 0.650	£ 0.463	[1]	£ 0.363	[2]
Before exceptional items and remeasurements
Statement [Line Items]
Revenue		£ 13,665		£ 13,360
Provision for bad and doubtful debts		(325)
Operating profit	£ 3,813	2,427		2,804
Finance income	65	35		70
Finance costs	(1,146)	(900)		(999)
Share of post-tax results of joint ventures and associates	148	66		88
Profit before tax	£ 2,880	£ 1,628		£ 1,963
Earnings per share (pence)
Basic earnings per share (continuing) (in GBP pence per share)	£ 0.614	£ 0.367		£ 0.462
Diluted earnings per share (continuing) (in GBP pence per share)	0.611	0.365		0.460
Basic earnings per share (continuing and discontinued) (in GBP pence per share)	0.710	0.464		0.554
Diluted earnings per share (continuing and discontinued) (in GBP pence per share)	£ 0.706	£ 0.461		£ 0.551
Exceptional items and remeasurements
Statement [Line Items]
Operating profit	£ 558	£ (26)		£ (525)
Finance income	(15)	23		(16)
Finance costs	74	47		(21)
Share of post-tax results of joint ventures and associates	(56)	(8)		(1)
Profit before tax	561	36		(563)
Tax	(589)	(26)		(8)
Profit after tax from continuing operations	£ (28)	£ 10		£ (571)
Earnings per share (pence)
Basic earnings per share (continuing) (in GBP pence per share)	£ (0.008)	£ 0.003		£ (0.165)
Diluted earnings per share (continuing) (in GBP pence per share)	(0.008)	0.003		(0.164)
Basic earnings per share (continuing and discontinued) (in GBP pence per share)	(0.056)	0.002		(0.189)
Diluted earnings per share (continuing and discontinued) (in GBP pence per share)	£ (0.056)	£ 0.002		£ (0.188)
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[3]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[4]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Consolidated statement of compr

Consolidated statement of comprehensive income - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Disclosure of analysis of other comprehensive income by item [line items]
Profit after tax from continuing operations	£ 2,183	£ 1,304	[1]	£ 1,030	[2]
Profit after tax from discontinued operations	171	337	[1]	235	[2]
Other comprehensive income from continuing operations
Remeasurement gains/(losses) on pension assets and post-retirement benefit obligations	2,172	1,658	[1]	(782)	[1]
Net gains/(losses) on equity instruments designated at fair value through other comprehensive income	12	46	[1]	(9)	[1]
Net losses in respect of cash flow hedging of capital expenditure	(1)	(12)	[1]	(17)	[1]
Tax on items that will never be reclassified to profit or loss	(496)	(472)	[1]	232	[1]
Total items from continuing operations that will never be reclassified to profit or loss	1,687	1,220	[1]	(576)	[1]
Items from continuing operations that may be reclassified subsequently to profit or loss:
Retranslation of net assets offset by net investment hedge	630	(1,347)	[1]	561	[1]
Net (losses)/gains in respect of cash flow hedges	(57)	67	[1]	(121)	[1]
Net gains/(losses) in respect of cost of hedging	1	20	[1]	(80)	[1]
Net (losses)/gains on investment in debt instruments measured at fair value through other comprehensive income	(11)	80	[1]	(15)	[1]
Share of other comprehensive income/(losses) of associates, net of tax	1	1	[1]	(5)	[1]
Tax on items that may be reclassified subsequently to profit or loss	15	(8)	[1]	33	[1]
Total items from continuing operations that may be reclassified subsequently to profit or loss	579	(1,187)	[1]	373	[1]
Other comprehensive income/(loss) for the year, net of tax from continuing operations	2,266	33	[1]	(203)	[1]
Other comprehensive income/(loss) for the year, net of tax from discontinued operations	211	(216)	[1]	38	[1]
Other comprehensive income/(loss) for the year, net of tax	2,477	(183)	[1]	(165)	[1]
Total comprehensive income for the year from continuing operations	4,449	1,337	[1]	827	[1]
Total comprehensive income for the year from discontinued operations	382	121	[1]	273	[1]
Total comprehensive income/(loss) for the year	4,831	1,458	[1]	1,100	[1]
Attributable to:
Equity shareholders of the parent	4,447	1,338	[1]	825	[1]
Non-controlling interests	2	(1)	[1]	2	[1]
From discontinued operations
Disclosure of analysis of other comprehensive income by item [line items]
Profit after tax from discontinued operations	171	337		235
Other comprehensive income from continuing operations
Remeasurement gains/(losses) on pension assets and post-retirement benefit obligations	309	(250)		58
Net losses in respect of cash flow hedging of capital expenditure	0	(2)		0
Tax on items that will never be reclassified to profit or loss	(94)	50		(20)
Total items from continuing operations that will never be reclassified to profit or loss	214	(213)		35
Items from continuing operations that may be reclassified subsequently to profit or loss:
Net (losses)/gains in respect of cash flow hedges	1	3		(1)
Net gains/(losses) in respect of cost of hedging	(4)	(6)		2
Tax on items that may be reclassified subsequently to profit or loss	0	0		2
Total items from continuing operations that may be reclassified subsequently to profit or loss	(3)	(3)		3
Other comprehensive income/(loss) for the year, net of tax	211	(216)		38
Total comprehensive income/(loss) for the year	382	121		273
Attributable to:
Equity shareholders of the parent	382	121	[1]	273	[1]
Aggregate continuing and discontinued operations
Items from continuing operations that may be reclassified subsequently to profit or loss:
Total comprehensive income/(loss) for the year	4,831	1,458		1,100
Attributable to:
Equity shareholders of the parent	£ 4,829	£ 1,459	[1]	£ 1,098	[1]
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Consolidated statement of chang

Consolidated statement of changes in equity - GBP (£) £ in Millions	Total		Aggregate continuing and discontinued operations	Total shareholders’ equity	Total shareholders’ equityAggregate continuing and discontinued operations	Share capital	Share premium account	Retained earnings	Retained earningsAggregate continuing and discontinued operations	Other equity reserves	[1]	Other equity reservesAggregate continuing and discontinued operations	[1]	Non-controlling interests	Non-controlling interestsAggregate continuing and discontinued operations
Equity, beginning balance at Mar. 31, 2019	£ 19,568			£ 19,548		£ 458	£ 1,314	£ 21,999		£ (4,223)				£ 20
Profit for the year	1,265	[2]		1,264				1,264						1
Other comprehensive (loss)/income for the year	(165)	[3]		(166)				(509)		343				1
Total comprehensive income/(loss) for the year	1,100	[3]	£ 1,100		£ 1,098				£ 755			£ 343			£ 2
Equity dividends	(892)			(892)				(892)
Scrip dividend-related share issue	(1)			(1)		12	(13)
Issue of treasury shares	17			17				17
Purchase of own shares	(6)			(6)				(6)
Share-based payments	19			19				19
Tax on share-based payments	3			3				3
Cash flow hedges transferred to the statement of financial position, net of tax	(15)			(15)						(15)
Equity, ending balance at Mar. 31, 2020	19,793			19,771		470	1,301	21,895		(3,895)				22
Profit for the year	1,641	[4]		1,640				1,640						1
Other comprehensive (loss)/income for the year	(183)	[3]		(181)				1,001		(1,182)				(2)
Total comprehensive income/(loss) for the year	1,458	[3]	1,458		1,459				2,641			(1,182)			(1)
Equity dividends	(1,413)			(1,413)				(1,413)
Scrip dividend-related share issue	(1)			(1)		4	(5)
Issue of treasury shares	17			17				17
Purchase of own shares	(2)			(2)				(2)
Share-based payments	27			27				27
Tax on share-based payments	(2)			(2)				(2)
Cash flow hedges transferred to the statement of financial position, net of tax	(17)			(17)						(17)
Equity, ending balance at Mar. 31, 2021	19,860			19,839		474	1,296	23,163		(5,094)				21
Profit for the year	2,354			2,353				2,353						1
Other comprehensive (loss)/income for the year	2,477			2,476				1,871		605				1
Total comprehensive income/(loss) for the year	4,831		£ 4,831		£ 4,829				£ 4,224			£ 605			£ 2
Equity dividends	(922)			(922)				(922)
Scrip dividend-related share issue	(1)			(1)		11	(12)
Issue of treasury shares	17			17				17
Increase (decrease) through treasury share transactions, equity	13			13			16	(3)
Share-based payments	43			43				43
Tax on share-based payments	7			7				7
Transfer of accumulated gains and losses on sale of equity investments	0			0				82		(82)
Cash flow hedges transferred to the statement of financial position, net of tax	8			8						8
Equity, ending balance at Mar. 31, 2022	£ 23,856			£ 23,833		£ 485	£ 1,300	£ 26,611		£ (4,563)				£ 23
[1]	For further details of other equity reserves, see note 28.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[3]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[4]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Consolidated statement of finan

Consolidated statement of financial position - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Non-current assets
Goodwill	£ 9,532	£ 4,588
Other intangible assets	3,272	1,443
Property, plant and equipment	57,532	47,043
Other non-current assets	303	293
Pension assets	3,885	1,747
Financial and other investments	830	755
Investments in joint ventures and associates	1,238	867
Derivative financial assets	305	542
Total non-current assets	76,897	57,278
Current assets
Inventories and current intangible assets	511	439
Trade and other receivables	3,715	2,919
Current tax assets	106	67
Financial and other investments	3,145	2,342
Derivative financial assets	282	457
Cash and cash equivalents	204	157
Assets held for sale	10,000	3,557
Total current assets	17,963	9,938
Total assets	94,860	67,216
Current liabilities
Borrowings	(12,121)	(3,737)
Derivative financial liabilities	(144)	(145)
Trade and other payables	(4,915)	(3,517)
Contract liabilities	(130)	(66)
Current tax liabilities	(32)	(75)
Provisions	(240)	(260)
Liabilities held for sale	(7,188)	(1,568)
Total current liabilities	(24,770)	(9,368)
Non-current liabilities
Borrowings	(33,344)	(27,483)
Derivative financial liabilities	(869)	(754)
Other non-current liabilities	(805)	(843)
Contract liabilities	(1,342)	(1,094)
Deferred tax liabilities	(6,765)	(4,815)
Pensions and other post-retirement benefit obligations	(810)	(1,032)
Provisions	(2,299)	(1,967)
Total non-current liabilities	(46,234)	(37,988)
Total liabilities	(71,004)	(47,356)
Net assets	23,856	19,860
Equity
Share capital	485	474
Share premium account	1,300	1,296
Retained earnings	26,611	23,163
Other equity reserves	(4,563)	(5,094)
Total shareholders’ equity	23,833	19,839
Non-controlling interests	23	21
Total equity	£ 23,856	£ 19,860

Consolidated cash flow statemen

Consolidated cash flow statement - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Cash flows from operating activities
Total operating profit from continuing operations		£ 4,371	£ 2,401	[1]	£ 2,279	[2]
Adjustments for:
Other fair value movements		(65)	(22)	[2]	0	[2]
Depreciation, amortisation and impairment		1,830	1,485	[2]	1,435	[2]
Gain on disposal of St William Homes LLP		(228)	0		0
Share-based payments		38	23	[2]	16	[2]
Changes in working capital		(223)	263	[2]	331	[2]
Changes in provisions		149	(167)	[2]	262	[2]
Changes in pensions and other post-retirement benefit obligations		(84)	(16)	[2]	(83)	[2]
Cash generated from operations – continuing operations		5,788	3,967	[2]	4,240	[2]
Tax paid		(298)	(91)	[2]	(92)	[2]
Net cash inflow from operating activities – continuing operations		5,490	3,876	[2]	4,148	[2]
Net cash inflow from operating activities – discontinued operations		782	585	[2]	470	[2]
Cash flows from investing activities
Acquisition of financial investments		(197)	(99)	[2]	(108)	[2]
Investments in joint ventures and associates		(265)	(81)	[2]	(82)	[2]
Disposal of financial investments		215	66	[2]	63	[2]
Disposal of interests in Quadgas HoldCo Limited		0	0	[2]	1,965	[2]
Disposal of interest in St William Homes LLP		413	0	[2]	0	[2]
Purchases of intangible assets		(446)	(399)	[2]	(295)	[2]
Purchases of property, plant and equipment		(5,098)	(4,209)	[2]	(4,291)	[2]
Disposals of property, plant and equipment		26	7	[2]	66	[2]
Dividends received from joint ventures, associates and other investments		166	80	[2]	75	[2]
Interest received		40	16	[2]	73	[2]
Net movements in short-term financial investments		(781)	(438)	[2]	12	[2]
Cash inflows on derivatives		17	225	[2]	58	[2]
Cash outflows on derivatives		(122)	(81)	[2]	(281)	[2]
Net cash flow used in investing activities – continuing operations		(13,885)	(4,939)	[2]	(2,884)	[2]
Net cash flow used in investing activities – discontinued operations		(125)	(177)	[2]	(311)	[2]
Cash flows from financing activities
Proceeds from issue of treasury shares		33	16	[2]	16	[2]
Purchase of own shares		(3)	(2)	[2]	(6)	[2]
Proceeds received from loans		12,347	5,150	[2]	3,921	[2]
Repayment of loans		(1,261)	(1,654)	[2]	(3,037)	[2]
Payments of lease liabilities		(117)	(107)	[2]	(115)	[2]
Net movements in short-term borrowings		(11)	(619)	[2]	(562)	[2]
Cash inflows on derivatives		20	17	[2]	46	[2]
Cash outflows on derivatives		(114)	(183)	[2]	(245)	[2]
Interest paid		(1,053)	(753)	[2]	(867)	[2]
Dividends paid to shareholders		(922)	(1,413)	[2]	(892)	[2]
Net cash flow from/(used in) financing activities – continuing operations		8,919	452	[2]	(1,741)	[2]
Net cash flow (used in)/from financing activities – discontinued operations		(1,150)	298	[2]	135	[2]
Net increase/(decrease) in cash and cash equivalents		31	95	[2]	(183)	[2]
Reclassification to held for sale		(11)	(4)	[2]	0	[2]
Exchange movements		5	(7)	[2]	4	[2]
Cash and cash equivalents at start of year		157	73	[2]	252	[2]
Cash and cash equivalents at end of year		204	157		73	[2]
Cash and cash equivalents if different from statement of financial position	[3]	182	157	[2]	73	[2]
National Grid Renewables and Emerald Energy Venture LLC Section Page Break
Cash flows from investing activities
Acquisition of, and contributions to National Grid Renewables and Emerald Energy Venture LLC and WPD		(16)	(26)	[2]	(139)	[2]
Western Power Distribution PLC
Cash flows from investing activities
Acquisition of, and contributions to National Grid Renewables and Emerald Energy Venture LLC and WPD	[4]	£ (7,837)	£ 0	[2]	£ 0	[2]
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[3]	Cash and cash equivalents at end of year are shown net of the Group’s bank overdraft as at 31 March 2022 of £22 million (2021: £nil; 2020: £nil).
[4]	Balance consists of cash consideration paid and cash acquired from WPD.

Consolidated statement of cha_2

Consolidated statement of changes in equity - Parenthetical (Details) £ in Millions	12 Months Ended
	Mar. 31, 2022GBP (£)
Gain on disposal of equity instruments measured at FVOCI	£ 12
Retained earnings
Gain on disposal of equity instruments measured at FVOCI	£ 82

Consolidated cash flow statem_2

Consolidated cash flow statement - Parenthetical (Details) £ in Millions	Mar. 31, 2022GBP (£)
Statement of cash flows [abstract]
Bank overdrafts	£ 22

Basis of preparation and recent

Basis of preparation and recent accounting developments	12 Months Ended
	Mar. 31, 2022
Accounting Policies, Changes In Accounting Estimates And Errors [Abstract]
Basis of preparation and recent accounting developments	1. Basis of preparation and recent accounting developments Accounting policies describe our approach to recognising and measuring transactions and balances in the year. The accounting policies applicable across the financial statements are shown below, whereas accounting policies that are specific to a component of the financial statements have been incorporated into the relevant note. This section also shows areas of judgement and key sources of estimation uncertainty in these financial statements. In addition, we have summarised new International Accounting Standards Board (IASB) accounting standards, amendments and interpretations and whether these are effective for this year end or in later years, explaining how significant changes are expected to affect our reported results. National Grid’s principal activities involve the transmission and distribution of electricity in Great Britain and electricity and gas in northeastern US. The Company is a public limited liability company incorporated and domiciled in England and Wales, with its registered office at 1–3 Strand, London WC2N 5EH. The Company, National Grid plc, which is the ultimate parent of the Group, has its primary listing on the London Stock Exchange and is also quoted on the New York Stock Exchange. These consolidated financial statements were approved for issue by the Board on 18 May 2022. These consolidated financial statements have been prepared in accordance with International Accounting Standards (IAS) and International Financial Reporting Standards (IFRS) and related interpretations as issued by the IASB and IFRS as adopted by the UK. They are prepared on the basis of all IFRS accounting standards and interpretations that are mandatory for the period ended 31 March 2022 and in accordance with the Companies Act 2006. The comparative financial information has also been prepared on this basis. The consolidated financial statements have been prepared on a historical cost basis, except for the recording of pension assets and liabilities, the revaluation of derivative financial instruments and certain commodity contracts and certain financial assets and liabilities measured at fair value. These consolidated financial statements are presented in pounds sterling, which is also the functional currency of the Company. The notes to the financial statements have been prepared on a continuing basis unless otherwise stated. A. Going concern As part of the Directors’ consideration of the appropriateness of adopting the going concern basis of accounting in preparing these financial statements, the Directors have considered the impact of the planned disposals of The Narragansett Electric Company (NECO) and the UK Gas Transmission business (see note 10) and the financing for the acquisition of PPL Western Power Distribution (WPD) (see note 33). The Directors have assessed the principal risks, including by modelling both a base case and a reasonable worst-case scenario. The main cash flow impacts identified in the reasonable worst-case scenario are: • additional potential working capital requirements in response to energy price increases driven by the wider energy market stability challenges and the conflict between Russia and Ukraine; • adverse impacts of inflation on our capex programme; • adverse impact from timing across the Group, i.e. a net under-recovery of allowed revenues or reductions in over-collections; • a significant reduction in cash collections driven by lower customer demand and increased bad debt in our US businesses and potential supplier defaults in our UK business; • higher cash outflow than expected following the Sellindge Interconnector fire; • higher operating costs than expected; or non-delivery of planned efficiencies across the Group; and • the potential impact of further significant storm costs in the US. As part of their analysis, the Board also considered the following potential levers at their discretion to improve the position identified by the analysis if the debt capital markets are not accessible: • the payment of dividends to shareholders; • significant changes in the phasing of the Group’s capital programme, with elements of non-essential works and programmes delayed; and • a number of further reductions in operating expenditure across the Group primarily related to workforce cost reductions in both the UK and the US. Having considered the reasonable worst-case scenario, the impact and timing of the planned strategic transactions, and the further levers at the Board’s discretion, the Group continues to have headroom against the Group’s committed facilities identified in note 33 to the financial statements. In addition to the above, the ability to raise new and extend existing financing was separately included in the analysis, and the Directors noted the c.£4.2 billion of new long-term senior debt issued in the period from 1 April to 31 March 2022 as evidence of the Group’s ability to continue to have access to the debt capital markets if needed. Based on the above, the Directors have concluded the Group is well placed to manage its financing and other business risks satisfactorily and have a reasonable expectation that the Group will have adequate resources to continue in operation for at least 12 months from the signing date of these consolidated financial statements. They therefore consider it appropriate to adopt the going concern basis of accounting in preparing the financial statements. 1. Basis of preparation and recent accounting developments continued B. Basis of consolidation The consolidated financial statements incorporate the results, assets and liabilities of the Company and its subsidiaries, together with a share of the results, assets and liabilities of joint operations. A subsidiary is defined as an entity controlled by the Group. Control is achieved where the Group is exposed to, or has the rights to, variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. The Group accounts for joint ventures and associates using the equity method of accounting, where the investment is carried at cost plus post-acquisition changes in the share of net assets of the joint venture or associate, less any provision for impairment. Losses in excess of the consolidated interest in joint ventures and associates are not recognised, except where the Company or its subsidiaries have made a commitment to make good those losses. Where necessary, adjustments are made to bring the accounting policies used in the individual financial statements of the Company, subsidiaries, joint operations, joint ventures and associates into line with those used by the Group in its consolidated financial statements under IFRS. Intercompany transactions are eliminated. The results of subsidiaries, joint operations, joint ventures and associates acquired or disposed of during the year are included in the consolidated income statement from the effective date of acquisition or up to the effective date of disposal, as appropriate. Acquisitions are accounted for using the acquisition method, where the purchase price is allocated to the identifiable assets acquired and liabilities assumed on a fair value basis and the remainder recognised as goodwill. C. Foreign currencies Transactions in currencies other than the functional currency of the Company or subsidiary concerned are recorded at the rates of exchange prevailing on the dates of the transactions. At each reporting date, monetary assets and liabilities that are denominated in foreign currencies are retranslated at closing exchange rates. Non-monetary assets are not retranslated unless they are carried at fair value. Gains and losses arising on the retranslation of monetary assets and liabilities are included in the income statement, except where the application of hedge accounting requires inclusion in other comprehensive income (see note 32(e)). On consolidation, the assets and liabilities of operations that have a functional currency different from the Company’s functional currency of pounds sterling, principally our US operations that have a functional currency of US dollars, are translated at exchange rates prevailing at the reporting date. Income and expense items are translated at the average exchange rates for the period where these do not differ materially from rates at the date of the transaction. Exchange differences arising are recognised in other comprehensive income and transferred to the consolidated translation reserve within other equity reserves (see note 28). D. Disposal of The Narragansett Electric Company As described further in note 10, on 17 March 2021, the Group signed an agreement to sell 100% of the share capital of a wholly owned subsidiary, NECO. Whilst all of the regulatory approvals are in place, the disposal of NECO was not finalised as at 31 March 2022 due to the appeal of one of these approvals by the Rhode Island Attorney General. The associated assets and liabilities have been presented as held for sale in the consolidated statement of financial position. As NECO does not represent either a major line of business or a geographical area of operations, it has not met the criteria for classification as a discontinued operation and therefore its results for the period are not separately disclosed on the face of the income statement. E. Disposal of UK Gas Transmission As described further in note 10, on 27 March 2022, the Group agreed to sell 100% of the UK Gas Transmission business to a new entity (the ‘Acquiring Entity’) in exchange for £4.2 billion cash consideration (subject to customary completion adjustments) and a 40% interest in the Acquiring Entity. The sale is expected to complete in the third quarter of the financial year ending 31 March 2023 subject to the receipt of all regulatory approvals. The Group’s 40% interest in the Acquiring Entity is expected to be classified as an associate on the basis that the Group will retain significant influence over the business through its retained stake. The Group has the ability to appoint two out of the seven Directors to the Board of the Acquiring Entity. On 27 March 2022, the Group also entered into a Further Acquisition Agreement (FAA) for the potential sale of the remaining 40% stake. The FAA is a put option that can be exercised by the purchaser either in the period between 1 January and 31 March 2023 or in the period between 1 April and 30 June 2023. The deferral of the option window is at our discretion (subject to change depending on the timing of the closing of the sale agreement). The Group classified the business as held for sale at the end of August 2021, when it became highly probable that the value of the business to the Group would be recovered through sale rather than continued ownership. As UK Gas Transmission represents a major separate line of business, the business has been classified separately as a discontinued operation for all periods presented in the consolidated income statement and statement of comprehensive income. Earnings per share (EPS) has also been shown split between continuing and discontinued operations. F. Areas of judgement and key sources of estimation uncertainty The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities, and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from these estimates. Information about such judgements and estimations is in the notes to the financial statements, and the key areas are summarised below. Areas of judgement that have the most significant effect on the amounts recognised in the financial statements are as follows: • in relation to the planned disposal of the UK Gas Transmission business, the key judgement that has been applied is the date from which the business qualified for classification as held for sale and a discontinued operation, as explained further in note 10; • in performing the WPD goodwill and indefinite-lived licence intangible assets impairment assessment, judgement has been applied over the forecast cash flow duration (see note 11); and • the judgement that, notwithstanding legislation enacted and targets committing the UK, New York State and Massachusetts to achieving net zero greenhouse gas emissions by 2050, these do not trigger a reassessment of the remaining useful economic lives of our gas network assets (see key sources of estimation uncertainty below and note 13). Key sources of estimation uncertainty that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year are as follows: • in performing the goodwill impairment assessment of the WPD group of cash-generating units, the key source of estimation uncertainty relates to the discount rate and terminal value assumptions used in the value-in-use calculations (see note 11); • the valuation of liabilities for pensions and other post-retirement benefits (see note 25); and • the cash flows applied in determining the environmental provisions, in particular relating to three US Superfund sites (see note 26). 1. Basis of preparation and recent accounting developments continued In addition, we also highlight the estimates made regarding the useful economic lives of our gas network assets due to the length over which they are being depreciated, the potential for new and evolving technologies over that period, and the range of potential pathways for meeting net zero targets (see note 13 for details and sensitivity analysis). In order to illustrate the impact that changes in assumptions for the valuation of pension assets and liabilities and cash flows for environmental provisions could have on our results and financial position, we have included sensitivity analyses in note 35. In performing our impairment assessment of goodwill and indefinite-lived licence intangible assets, we have sensitised our forecasts to factor in adjustments to key inputs to each model (see note 11). Information on what we believe to be a reasonably possible range of outcomes on the recoverability of customer receivables is included in note 19. G. Accounting policy choices IFRS provides certain options available within accounting standards. Choices we have made, and continue to make, include the following: • Presentational formats: we use the nature of expense method for our income statement and aggregate our statement of financial position to net assets and total equity. • Financial instruments: we normally opt to apply hedge accounting in most circumstances where this is permitted (see note 32(e)). H. New IFRS accounting standards and interpretations effective for the year ended 31 March 2022 The Group early adopted the following amendments to standards which have had no material impact on the Group’s results or financial statement disclosures: • amendments to IFRS 16 ‘Leases – COVID-19-Related Rent Concessions’; • amendments to IFRS 3 ‘Definition of a Business’; and • amendments to IAS 1 and IAS 8 ‘Definition of Material’. In April 2021, the IFRS IC (Interpretation Committee) also issued an agenda decision in relation to the accounting treatment for configuration and customisation costs in a cloud computing arrangement. This guidance clarified that in order for an intangible asset to be capitalised in relation to customisation and configuration costs in a cloud computing arrangement, it is necessary for there to be control of the underlying software asset or for there to be a separate intangible asset which meets the definition in IAS 38 Intangible Assets. As at 31 March 2022, the Group has recognised a cumulative adjustment against software intangible assets of £34 million for previously capitalised customisation and configuration relating to its continuing operations. The Group has also considered the application of the new accounting guidance for its comparative periods and concluded that it does not have a material impact. Accordingly, no comparative periods have been restated. I. New IFRS accounting standards and interpretations not yet adopted The following new accounting standards and amendments to existing standards have been issued but are not yet effective: • IFRS 17 ‘Insurance Contracts’; • amendments to IFRS 3 ‘Business Combinations’; • amendments to IAS 12 ‘Deferred Tax Related to Assets and Liabilities Arising from a Single Transaction’; • amendments to IAS 16 ‘Property, Plant and Equipment’; • amendments to IAS 37 ‘Provisions, Contingent Liabilities and Contingent Assets’; • amendments to IAS 1 ‘Presentation of Financial Statements’; • amendments to IAS 8 ‘Accounting Policies, Changes in Accounting Estimates and Errors’; • annual improvements to IFRS standards 2018-2020; and • amendments to IFRS Practice Statement 2 – making materiality judgements. The Group is currently assessing the impact of the above standards, but they are not expected to have a material impact. The Group has not adopted any other standard, amendment or interpretation that has been issued but is not yet effective.

Segmental analysis

Segmental analysis	12 Months Ended
	Mar. 31, 2022
Disclosure of operating segments [abstract]
Segmental analysis	2. Segmental analysis This note sets out the financial performance for the year split into the different parts of the business (operating segments). The performance of these operating segments is monitored and managed on a day-to-day basis. Revenue and the results of the business are analysed by operating segment, based on the information the Board of Directors uses internally for the purposes of evaluating the performance of each operating segment and determining resource allocation between them. The Board is National Grid’s chief operating decision maker (as defined by IFRS 8 ‘Operating Segments’) and assesses the profitability of operations principally on the basis of operating profit before exceptional items and remeasurements (see note 5). As a matter of course, the Board also considers profitability by segment, excluding the effect of timing. However, the measure of profit disclosed in this note is operating profit before exceptional items and remeasurements as this is the measure that is most consistent with the IFRS results reported within these financial statements. As a result of the new operating model, the operating segments that were reported up to the Board have changed during the period to align with the six business units that will continue to operate, and the UK Gas Transmission business that is expected to be disposed of, which is now considered a discontinued operation (see note 10). Five of these continuing businesses meet the size criteria set out in the accounting standards to be treated as reportable operating segments. The other operating segment, remaining businesses that are not operating segments and the corporate centre activities are reported to the Board of Directors on an aggregated basis. The following table describes the main activities for each reportable operating segment within continuing operations: UK Electricity Transmission The high-voltage electricity transmission networks in England and Wales. UK Electricity Distribution The electricity distribution networks of WPD in the East Midlands, West Midlands and South West of England and South Wales. UK Electricity System Operator The Great Britain system operator. New England Gas distribution networks, electricity distribution networks and high-voltage electricity transmission networks in New England. New York Gas distribution networks, electricity distribution networks and high-voltage electricity transmission networks in New York. The UK Gas Transmission business, which owns the high-pressure gas transmission networks in Great Britain and gas system operator in Great Britain and includes the regulated gas metering operations (which was previously reported within NGV and Other), is now a discontinued operation and classified as held for sale (see note 10). Therefore, while it is still a reportable operating segment, it is no longer presented within continuing operations. The National Grid Ventures (NGV) operating segment is outside our regulated core business and operates in competitive markets across the UK and the US. The business comprises all commercial operations in LNG at the Isle of Grain in the UK, our electricity generation business in the US, our electricity interconnectors and our investment in National Grid Renewables Development LLC, with a focus on investment and future activities in emerging growth areas. NGV does not meet the thresholds set out in IFRS 8 to be identified as a separate reportable segment and therefore its results are not required to be separately presented. Other activities that do not form part of any of the segments in the above table or NGV primarily relate to our UK property business together with insurance and corporate activities in the UK and US and the Group’s investments in technology and innovation companies through National Grid Partners. (a) Revenue Revenue primarily represents the sales value derived from the generation, transmission and distribution of energy, together with the sales value derived from the provision of other services to customers. Refer to note 3 for further details. Sales between operating segments are priced considering the regulatory and legal requirements to which the businesses are subject. The analysis of revenue by geographical area is on the basis of destination. There are no material sales between the UK and US geographical areas. 2022 2021¹ 2020¹ Total £m Sales between segments £m Sales to third parties £m Total Sales Sales Total Sales Sales Operating segments – continuing operations: UK Electricity Transmission 2,035 (7) 2,028 1,974 (10) 1,964 1,986 (8) 1,978 UK Electricity Distribution 1,482 (14) 1,468 — — — — — — UK Electricity System Operator 3,455 (18) 3,437 2,018 — 2,018 1,716 — 1,716 New England 4,550 — 4,550 4,214 — 4,214 4,235 — 4,235 New York 5,561 — 5,561 4,605 — 4,605 4,601 — 4,601 NGV and Other 1,405 — 1,405 864 — 864 834 (4) 830 Total revenue from continuing operations 18,488 (39) 18,449 13,675 (10) 13,665 13,372 (12) 13,360 Split by geographical areas – continuing operations: UK 7,803 4,368 4,102 US 10,646 9,297 9,258 Total revenue from continuing operations 18,449 13,665 13,360 1. Comparative amounts have been re-presented to reflect the new operating segments and the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 2. In connection with the disposal of St William Homes LLP in the year the Group released deferred income within NGV and Other of £189 million related to deferred profits from previous property sales (see note 5). 2. Segmental analysis continued (b) Operating profit A reconciliation of the operating segments’ measure of profit to profit before tax from continuing operations is provided below. Further details of the exceptional items and remeasurements are provided in note 5. Before exceptional items Exceptional items and remeasurements After exceptional items and remeasurements 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ £m £m £m £m £m £m £m £m £m Operating segments – continuing operations: UK Electricity Transmission 1,067 1,094 1,109 (12) (14) (5) 1,055 1,080 1,104 UK Electricity Distribution 909 — — — — — 909 — — UK Electricity System Operator 7 (60) 211 (2) 7 1 5 (53) 212 New England 743 611 523 21 3 (53) 764 614 470 New York 780 665 835 315 30 (465) 1,095 695 370 NGV and Other 307 117 126 236 (52) (3) 543 65 123 Total operating profit from continuing operations 3,813 2,427 2,804 558 (26) (525) 4,371 2,401 2,279 Split by geographical area – continuing operations: UK 2,234 1,113 1,422 224 (57) (8) 2,458 1,056 1,414 US 1,579 1,314 1,382 334 31 (517) 1,913 1,345 865 Total operating profit from continuing operations 3,813 2,427 2,804 558 (26) (525) 4,371 2,401 2,279 1. Comparative amounts have been re-presented to reflect the new operating segments and the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. Before exceptional items Exceptional items After exceptional items 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ £m £m £m £m £m £m £m £m £m Reconciliation to profit before tax: Operating profit from continuing operations 3,813 2,427 2,804 558 (26) (525) 4,371 2,401 2,279 Share of post-tax results of joint ventures and associates 148 66 88 (56) (8) (1) 92 58 87 Finance income 65 35 70 (15) 23 (16) 50 58 54 Finance costs (1,146) (900) (999) 74 47 (21) (1,072) (853) (1,020) Profit before tax from continuing operations 2,880 1,628 1,963 561 36 (563) 3,441 1,664 1,400 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. (c) Capital expenditure Capital expenditure represents additions to property, plant and equipment and non-current intangibles but excludes additional investments in and loans to joint ventures and associates. Net book value of property, plant and Capital expenditure Depreciation, amortisation 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ £m £m £m £m £m £m £m £m £m Operating segments: UK Electricity Transmission 14,678 14,000 13,463 1,195 984 951 (508) (460) (431) UK Electricity Distribution 12,522 — — 899 — — (158) — — UK Electricity System Operator 404 379 336 108 88 92 (83) (47) (38) New England 11,485 10,165 13,127 1,561 1,437 1,365 (364) (389) (373) New York 18,676 16,467 16,920 1,960 1,738 1,822 (537) (453) (436) NGV and Other 3,039 2,750 2,490 462 480 562 (180) (136) (157) Total 60,804 43,761 46,336 6,185 4,727 4,792 (1,830) (1,485) (1,435) Split by geographical area – continuing operations: UK 30,131 16,627 15,706 2,546 1,504 1,560 (879) (596) (579) US 30,673 27,134 30,630 3,639 3,223 3,232 (951) (889) (856) Total 60,804 43,761 46,336 6,185 4,727 4,792 (1,830) (1,485) (1,435) Asset type: Property, plant and equipment 57,532 42,424 45,160 5,714 4,335 4,465 (1,544) (1,317) (1,286) Non-current intangible assets 3,272 1,337 1,176 471 392 327 (286) (168) (149) Total 60,804 43,761 46,336 6,185 4,727 4,792 (1,830) (1,485) (1,435)

Revenue

Revenue	12 Months Ended
	Mar. 31, 2022
Disclosure of disaggregation of revenue from contracts with customers [abstract]
Revenue	3. Revenue Revenue arises in the course of ordinary activities and principally comprises: • transmission services; • distribution services; and • generation services. Transmission services, distribution services and certain other services (excluding rental income but including metering) fall within the scope of IFRS 15 ‘Revenue from Contracts with Customers’, whereas generation services (which solely relate to the contract with the Long Island Power Authority (LIPA) in the US) are accounted for under IFRS 16 ‘Leases’ as rental income, also presented within revenue. Revenue is recognised to reflect the transfer of goods or services to customers at an amount that reflects the consideration to which the Group expects to be entitled to in exchange for those goods or services and excludes amounts collected on behalf of third parties and value added tax. The Group recognises revenue when it transfers control over a product or service to a customer. Revenue in respect of regulated activities is determined by regulatory agreements that set the price to be charged for services in a given period based on pre-determined allowed revenues. Variances in service usage can result in actual revenue collected exceeding (over-recoveries) or falling short (under-recoveries) of allowed revenues. Where regulatory agreements allow the recovery of under-recoveries or require the return of over-recoveries, the allowed revenue for future periods is typically adjusted. In these instances, no assets or liabilities are recognised for under- or over-recoveries respectively, because the adjustment relates to future services that have not yet been delivered. Below, we include a description of principal activities, by reportable segment, from which the Group generates its revenue. For more detailed information about our segments, see note 2. (a) UK Electricity Transmission The UK Electricity Transmission segment principally generates revenue by providing electricity transmission services in England and Wales. Our business operates as a monopoly regulated by Ofgem, which has established price control mechanisms that set the amount of annual allowed returns our business can earn (along with the Scottish and Offshore transmission operators amongst others). The transmission of electricity encompasses the following principal services: • the supply of high-voltage electricity – revenue is recognised based on usage. Our performance obligation is satisfied over time as our customers make use of our network. We bill monthly in arrears and our payment terms are up to 60 days. Price is determined prior to our financial year end with reference to the regulated allowed returns and estimated annual volumes; and • construction work (principally for connections) – revenue is recognised over time, as we provide access to our network. Customers can either pay over the useful life of the connection or upfront. Where the customer pays upfront, revenues are deferred as a contract liability and released over the life of the asset. For other construction where there is no consideration for any future services, for example diversions, revenues are recognised as the construction work is completed. (b) UK Electricity Distribution The UK Electricity Distribution segment principally generates revenue by providing electricity distribution services in the Midlands and South West of England and South Wales. Similar to UK Electricity Transmission, UK Electricity Distribution operates as a monopoly in the jurisdictions that it operates in and is regulated by Ofgem. The distribution of electricity encompasses the following principal services: • electricity distribution – revenue is recognised based on usage by customers (over time), based upon volumes and price. The price control mechanism in place that determines our annual allowances is similar to UK Electricity Transmission. Revenues are billed monthly and payment terms are typically within 14 days; and • construction work (principally for connections) – revenue is recognised over time as we provide access to our network. Where the customer pays upfront, revenues are deferred as a contract liability and released over the life of the asset. For other construction where there is no consideration for any future services, revenues are recognised as the construction is completed. (c) UK Electricity System Operator The UK System Operator earns revenue for balancing supply and demand of electricity on Great Britain’s electricity transmission system, where it acts as principal. Balancing services are regulated by Ofgem and revenue is recognised as the service is provided. The System Operator also collects revenues on behalf of transmission operators, principally National Grid Electricity Transmission plc and the Scottish and Offshore transmission operators, from users (electricity suppliers) who connect to or use the transmission system. As the System Operator acts as an agent in this capacity, it therefore records transmission network revenues net of payments to transmission operators. (d) New England The New England segment principally generates revenue by providing electricity and gas distribution services and high voltage electricity transmission services in New England. Distribution services are regulated by the Massachusetts Department of Public Utilities (MADPU) and the Rhode Island Public Utilities Commission (RIPUC) and transmission services are regulated by the Federal Energy Regulatory Commission (FERC), both of whom regulate the rates that can be charged to customers. The distribution of electricity and gas and the provision of electricity transmission facilities encompasses the following principal services: • electricity and gas distribution and electricity transmission – revenue is recognised based on usage by customers (over time). Revenues are billed monthly and payment terms are 30 days; and • construction work (principally for connections) – revenue is recognised over time as we provide access to our network. Where the customer pays upfront, revenues are deferred as a contract liability or customer contributions (where they relate to government entities) and released over the life of the connection. 3. Revenue continued (e) New York The New York segment principally generates revenue by providing electricity and gas distribution services and high-voltage electricity transmission services in New York. Distribution services are regulated by the New York Public Service Commission (NYPSC) and transmission services are regulated by the FERC, both of whom regulate the rates that can be charged to customers. The distribution of electricity and gas and the provision of electricity transmission facilities encompasses the following principal services: • electricity and gas distribution and electricity transmission – revenue is recognised based on usage by customers (over time). Revenues are billed monthly and payment terms are 30 days; and • construction work (principally for connections) – revenue is recognised over time as we provide access to our network. Where the customer pays upfront, revenues are deferred as a contract liability or customer contributions (where they relate to government entities) and released over the life of the connection. (f) NGV and Other NGV and Other generates revenue from electricity interconnectors, LNG at the Isle of Grain, National Grid Renewables, our UK commercial property business, rental income and insurance. The Group recognises revenue from transmission services through interconnectors and LNG importation at the Isle of Grain by means of customers’ use of capacity and volumes. Revenue is recognised over time and is billed monthly. Payment terms are up to 30 days. Revenues in respect of certain wholly owned interconnector subsidiaries are subject to a cap and floor regime constructed by Ofgem. Where an interconnector expects to breach its total five-year cap, a provision and reduction in revenue is recognised in the current reporting period (see note 26). Where an interconnector does not expect to reach its five-year floor, either an asset will be recognised where a future inflow of economic benefits is considered virtually certain, or a contingent asset will be disclosed where the future inflow is concluded to be probable. Electricity generation revenue is earned from the provision of energy services and supply capacity to produce energy for the use of customers of LIPA through a power supply agreement where LIPA receives all of the energy and capacity from the asset until at least 2025. The arrangement is treated as an operating lease within the scope of the leasing standard where we act as lessor; with rental income being recorded as other income, which forms part of total revenue. Lease payments (capacity payments) are recognised on a straight-line basis and variable lease payments are recognised as the energy is generated. Other revenue in the scope of IFRS 15 principally includes sales of renewables projects from National Grid Renewables to Emerald Energy Venture LLC (Emerald), which is jointly controlled by National Grid and Washington State Investment Board (WSIB) (see note 16). National Grid Renewables develops wind and solar generation assets in the US, whilst Emerald has a right of first refusal to buy, build and operate those assets. Revenue is recognised as it is earned. Other revenue, recognised in accordance with standards other than IFRS 15, includes property sales by our UK commercial property business (including sales to our 50% share in the St William joint venture which was sold on 15 March 2022) and rental income. Property sales are recorded at a point in time (when the sale is legally completed) and rental income is recorded over time. (g) Disaggregation of revenue In the following tables, revenue is disaggregated by primary geographical market and major service lines. The table below reconciles disaggregated revenue with the Group’s reportable segments (see note 2). Revenue for the year ended 31 March 2022 UK Electricity Transmission UK Electricity Distribution UK Electricity System Operator New New NGV and Other Total Revenue under IFRS 15 Transmission 1,983 — — 52 405 627 3,067 Distribution — 1,375 — 4,434 5,110 — 10,919 System Operator — — 3,418 — — — 3,418 Other 1 35 89 19 10 10 147 310 Total IFRS 15 revenue 2,018 1,464 3,437 4,496 5,525 774 17,714 Other revenue Generation — — — — — 373 373 Other 2 10 4 — 54 36 258 362 Total other revenue 10 4 — 54 36 631 735 Total revenue from continuing operations 2,028 1,468 3,437 4,550 5,561 1,405 18,449 1. The UK Electricity Transmission and UK Electricity Distribution other IFRS 15 revenue principally relates to engineering recharges, which are the recovery of costs incurred for construction work requested by customers, such as the rerouting of existing network assets. UK Electricity System Operator other IFRS 15 revenue reflects the net income from its role as agent in respect of transmission network revenues. Within NGV and Other, the other IFRS 15 revenue principally relates to revenue generated from our NG Renewables business. 2. Other revenue, recognised in accordance with accounting standards other than IFRS 15, includes property sales by our UK commercial property business and rental income. 3. Revenue continued (g) Disaggregation of revenue continued Geographical split for the year ended 31 March 2022 UK Electricity Transmission UK Electricity Distribution UK Electricity System Operator New England New NGV and Total Revenue under IFRS 15 UK 2,018 1,464 3,437 — — 646 7,565 US — — — 4,496 5,525 128 10,149 Total IFRS 15 revenue 2,018 1,464 3,437 4,496 5,525 774 17,714 Other revenue UK 10 4 — — — 224 238 US — — — 54 36 407 497 Total other revenue 10 4 — 54 36 631 735 Total revenue from continuing operations 2,028 1,468 3,437 4,550 5,561 1,405 18,449 Revenue for the year ended 31 March 2021 UK Electricity Transmission UK Electricity Distribution UK Electricity System Operator New New NGV and Total¹ Revenue under IFRS 15 Transmission 1,875 — — 74 329 316 2,594 Distribution — — — 4,091 4,226 — 8,317 System Operator — — 2,076 — — — 2,076 Other 2 67 — (61) 8 7 76 97 Total IFRS 15 revenue 1,942 — 2,015 4,173 4,562 392 13,084 Other revenue Generation — — — — — 376 376 Other 3 22 — 3 41 43 96 205 Total other revenue 22 — 3 41 43 472 581 Total revenue from continuing operations 1,964 — 2,018 4,214 4,605 864 13,665 Geographical split for the year ended 31 March 2021 UK Electricity Transmission £m UK Electricity Distribution UK Electricity System Operator New New NGV and Total¹ Revenue under IFRS 15 UK 1,942 — 2,015 — — 327 4,284 US — — — 4,173 4,562 65 8,800 Total IFRS 15 revenue 1,942 — 2,015 4,173 4,562 392 13,084 Other revenue UK 22 — 3 — — 59 84 US — — — 41 43 413 497 Total other revenue 22 — 3 41 43 472 581 Total revenue from continuing operations 1,964 — 2,018 4,214 4,605 864 13,665 1. Comparative amounts have been re-presented to reflect the new operating segments and the classification of the UK Gas Transmission business as a discontinued operation. See notes 1, 2 and 10 for further information. 2. The UK Electricity Transmission other IFRS 15 revenue principally relates to engineering recharges, which are the recovery of costs incurred for construction work requested by customers, such as the rerouting of existing network assets. UK Electricity System Operator other IFRS 15 revenue reflects the net income from its role as agent in respect of transmission network revenues. Within NGV and Other, the other IFRS 15 revenue principally relates to revenue generated from our NG Renewables business. 3. Other revenue, recognised in accordance with accounting standards other than IFRS 15, principally includes property sales by our UK commercial property business and rental income reported in NGV and Other. 3. Revenue continued (g) Disaggregation of revenue continued Revenue for the year ended 31 March 2020 UK Electricity Transmission UK Electricity Distribution UK Electricity System Operator New New NGV and Total¹ Revenue under IFRS 15 Transmission 1,898 — — 77 348 309 2,632 Distribution — — — 4,114 4,205 — 8,319 System Operator — — 1,610 — — — 1,610 Other 2 69 — 94 6 6 51 226 Total IFRS 15 revenue 1,967 — 1,704 4,197 4,559 360 12,787 Other revenue Generation — — — — — 369 369 Other 3 11 — 12 38 42 101 204 Total other revenue 11 — 12 38 42 470 573 Total revenue from continuing operations 1,978 — 1,716 4,235 4,601 830 13,360 Geographical split for the year ended 31 March 2020 UK Electricity Transmission £m UK Electricity Distribution UK Electricity System Operator New New NGV and Total¹ Revenue under IFRS 15 UK 1,967 — 1,704 — — 322 3,993 US — — — 4,197 4,559 38 8,794 Total IFRS 15 revenue 1,967 — 1,704 4,197 4,559 360 12,787 Other revenue UK 11 — 12 — — 86 109 US — — — 38 42 384 464 Total other revenue 11 — 12 38 42 470 573 Total revenue from continuing operations 1,978 — 1,716 4,235 4,601 830 13,360 1. Comparative amounts have been re-presented to reflect the new operating segments and the classification of the UK Gas Transmission business as a discontinued operation. See notes 1, 2 and 10 for further information. 2. The UK Electricity Transmission other IFRS 15 revenue principally relates to engineering recharges, which are the recovery of costs incurred for construction work requested by customers, such as the rerouting of existing network assets. UK Electricity System Operator other IFRS 15 revenue reflects the net income from its role as agent in respect of transmission network revenues. Within NGV and Other, the other IFRS 15 revenue principally relates to revenue generated from our NG Renewables business. 3. Other revenue, recognised in accordance with accounting standards other than IFRS 15, principally includes property sales by our UK commercial property business and rental income reported in NGV and Other. Contract liabilities (see note 23) represent revenue to be recognised in future periods relating to contributions in aid of construction of £1,472 million (2021: £1,160 million; 2020: £1,158 million). Contract liabilities in the years ended 31 March 2021 and 2020 included amounts in respect of the UK Gas Transmission business of £136 million and £136 million respectively. Revenue is recognised over the life of the asset. The asset lives for connections in UK Electricity Transmission, UK Electricity Distribution, New England and New York are 40 years, 69 years, 51 years and up to 48 years respectively. The weighted average amortisation period is 31 years. Future revenues in relation to unfulfilled performance obligations not yet received in cash amount to £5.2 billion (2021: £4.8 billion; 2020: £3.1 billion). £1.7 billion (2021: £1.6 billion; 2020: £1.5 billion) relates to connection contracts in UK Electricity Transmission which will be recognised as revenue over 25 years and £3.0 billion (2021: £3.0 billion; 2020: £1.5 billion) relates to revenues to be earned under Grain LNG contracts until 2045. The remaining amount will be recognised as revenue over 3 years.

Other operating income and cost

Other operating income and costs	12 Months Ended
	Mar. 31, 2022
Analysis of income and expense [abstract]
Other operating income and costs	4. Other operating income and costs Below we have presented separately certain items included in our operating costs from continuing operations. These include a breakdown of payroll costs (including disclosure of amounts paid to key management personnel) and fees paid to our auditors. Other operating income includes gains arising on disposal of interests in other entities. 2022 2021¹ 2020¹ £m £m £m (Gain) on disposal of St William Homes LLP (note 5) (228) — — Depreciation, amortisation and impairment 1,830 1,485 1,435 Payroll costs 1,794 1,638 1,558 Purchases of electricity 1,280 1,130 1,403 Purchases of gas 1,666 1,250 1,316 Property and other taxes 1,202 1,105 1,100 UK Electricity Balancing costs 3,152 1,875 1,317 Other 3,215 2,456 2,718 Other operating (income)/costs 13,911 10,939 10,847 Provision for bad and doubtful debts 167 325 234 Total operating costs from continuing operations 14,078 11,264 11,081 Operating costs from continuing operations include: Inventory consumed 436 312 315 Research and development expenditure 11 12 9 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. (a) Payroll costs 2022 2021¹ 2020¹ £m £m £m Wages and salaries 2 2,563 2,170 2,081 Social security costs 201 156 152 Defined contribution scheme costs 81 67 62 Defined benefit pension costs 185 126 125 Share-based payments 38 23 16 Severance costs (excluding pension costs) 5 9 1 3,073 2,551 2,437 Less: payroll costs capitalised (1,279) (913) (879) Total payroll costs from continuing operations 1,794 1,638 1,558 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 2. Included within wages and salaries are US other post-retirement benefit costs of £39 million (2021: £43 million; 2020: £45 million). For further information refer to note 25. (b) Number of employees 31 March 2022 Monthly average 2022 31 March 2021¹ Monthly average 2021 1 31 March 2020¹ Monthly average 2020 1 UK 11,960 11,393 4,468 4,333 4,185 4,095 US 17,332 17,314 17,026 16,821 16,748 16,679 Total number of employees (continuing operations) 29,292 28,707 21,494 21,154 20,933 20,774 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 4. Other operating income and costs continued (c) Key management compensation 2022 2021 2020 £m £m £m Short-term employee benefits 7 7 7 Compensation for loss of office — — 1 Post-employment benefits 1 1 1 Share-based payments 5 4 3 Total key management compensation 13 12 12 Key management compensation relates to the Board, including the Executive Directors and Non-executive Directors for the years presented. (d) Auditors’ remuneration Auditors’ remuneration is presented below in accordance with the requirements of the Companies Act 2006 and the principal accountant fees and services disclosure requirements of Item 16C of Form 20-F: 2022 2021 2020 £m £m £m Audit fees payable to the Parent Company’s auditors and their associates in respect of: Audit of the Parent Company’s individual and consolidated financial statements 1 2.7 2.5 1.9 The auditing of accounts of any associate of the Company 8.9 8.1 8.7 Other services supplied 2 7.3 6.4 6.3 18.9 17.0 16.9 Total other services 3 All other fees: Other assurance services 4 0.9 0.8 0.6 Other non-audit services not covered above 5 0.1 2.0 0.5 1.0 2.8 1.1 Total auditors’ remuneration 19.9 19.8 18.0 1. Audit fees in each year represent fees for the audit of the Company’s financial statements and regulatory reporting for the years ended 31 March 2022, 2021 and 2020. 2. Other services supplied represent fees payable for services in relation to other statutory filings or engagements that are required to be carried out by the auditors. In particular, this includes fees for reports under section 404 of the US Public Company Accounting Reform and Investor Protection Act of 2002 (Sarbanes-Oxley), audit reports on regulatory returns and the review of interim financial statements for the six-month periods ended 30 September 2021, 2020 and 2019 respectively. 3. There were no tax compliance or tax advisory fees and no audit-related fees as described in Item 16C(b) of Form 20-F. 4. In all years, principally relates to assurance services provided in relation to comfort letters for debt issuances and, in 2021, also includes amounts related to capacity market auction monitoring services. 5. For 2021, includes the class 1 Circular in respect of the acquisition of WPD announced on 18 March 2021. In 2020, other assurance services include auction monitor work on Contracts for Difference, a review of controls over our data on New York customers and IT project assurance. The Audit & Risk Committee considers and makes recommendations to the Board, to be put to shareholders for approval at each AGM, in relation to the appointment, re-appointment, removal and oversight of the Company’s independent auditors. The Committee also considers and approves the audit fees on behalf of the Board in accordance with the Competition and Market Authority Audit Order 2014. The auditors’ remuneration is then put to shareholders at each AGM. Certain services are prohibited from being performed by the external auditors under the Sarbanes-Oxley Act. Of the above services, none were prohibited.

Exceptional items and remeasure

Exceptional items and remeasurements	12 Months Ended
	Mar. 31, 2022
Exceptional Items And Remeasurements [Abstract]
Exceptional items and remeasurements	5. Exceptional items and remeasurements To monitor our segmental financial performance, we use a profit measure that excludes certain income and expenses. We call that measure ‘adjusted profit’. Adjusted profit (which excludes exceptional items and remeasurements as defined below) is used by management to monitor financial performance as it is considered that it aids the comparability of our reported financial performance from year to year. We exclude items from adjusted profit because, if included, these items could distort understanding of our performance for the year and the comparability between periods. This note analyses these items, which are included in our results for the year but are excluded from adjusted profit. Exceptional items and remeasurements from continuing operations 2022 2021 1 2020 1 £m £m £m Included within operating profit Exceptional items: Release of St William Homes LLP deferred income 189 — — Net gain on disposal of St William Homes LLP 228 — — New operating model implementation costs and cost efficiency programme (66) (50) — Transaction and separation costs (223) (24) — Environmental insurance recovery 38 — — Changes in environmental provisions — 14 (400) 166 (60) (400) Remeasurements – commodity contract derivatives 392 34 (125) 558 (26) (525) 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. As disclosed in note 8, the Group also presents an adjusted earnings per share measure that is calculated before exceptional items and remeasurements. This measure is presented after tax and therefore details of tax exceptional items and the tax effect of exceptional items and remeasurements are also provided in this note. 2022 2021 1 2020 1 £m £m £m Included within finance income and costs Remeasurements: Net gains/(losses) on financing derivatives 74 47 (21) Net (losses)/gains on financial assets at fair value through profit and loss (15) 23 (16) 59 70 (37) Included within share of post-tax results of joint ventures and associates Remeasurements: Remeasurements – net losses on financial instruments (56) (8) (1) Total included within profit/(loss) before tax 561 36 (563) Included within tax Exceptional items – movements arising on items not included in profit before tax: Deferred tax charge arising as a result of UK tax rate change (458) — (148) Tax on exceptional items (28) 8 103 Tax on remeasurements (103) (34) 37 (589) (26) (8) Total exceptional items and remeasurements after tax (28) 10 (571) Analysis of total exceptional items and remeasurements after tax Exceptional items after tax (320) (52) (445) Remeasurements after tax 292 62 (126) Total exceptional items and remeasurements after tax (28) 10 (571) 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 5. Exceptional items and remeasurements continued Exceptional items Management uses an exceptional items framework that has been discussed and approved by the Audit & Risk Committee. This follows a three-step process which considers the nature of the event, the financial materiality involved and any particular facts and circumstances. In considering the nature of the event, management focuses on whether the event is within the Group’s control and how frequently such an event typically occurs. With respect to restructuring costs, these represent additional expenses incurred that are not related to the normal business and day-to-day activities. In determining the facts and circumstances, management considers factors such as ensuring consistent treatment between favourable and unfavourable transactions, the precedent for similar items, the number of periods over which costs will be spread or gains earned, and the commercial context for the particular transaction. The exceptional items framework was last updated in March 2022 and reflects the latest disclosure requirements arising in respect of FRC guidance issued in the year. Items of income or expense that are considered by management for designation as exceptional items include significant restructurings, write-downs or impairments of non-current assets, significant changes in environmental or decommissioning provisions, integration of acquired businesses, gains or losses on disposals of businesses or investments and significant debt redemption costs as a consequence of transactions such as significant disposals or issues of equity, and the related tax, as well as deferred tax arising on changes to corporation tax rates. Costs arising from restructuring programmes include redundancy costs. Redundancy costs are charged to the consolidated income statement in the year in which a commitment is made to incur the costs and the main features of the restructuring plan have been announced to affected employees. Set out below are details of the transactions against which we have considered the application of our exceptional items framework in each of the years for which results are presented. No COVID-19-related costs incurred have been recognised as exceptional in any of the years presented. 2022 Net gain on disposal of St William Homes LLP and release of deferred income During the year, the Group recognised a gain of £228 million on the disposal of its entire 50% equity interest in the St William Homes LLP joint venture to The Berkeley Group plc for cash consideration of £413 million (see note 16). In connection with the disposal, the Group also released deferred income of £189 million which related to deferred profits from previous property sales to St William Homes LLP. We have concluded that the release of the deferred income should be classified as exceptional given the crystallisation event for the release is the sale of the Group’s equity interest in St William Homes LLP. New operating model implementation costs and cost efficiency programme The Group incurred a further £66 million of costs in relation to the design and implementation of our new operating model and the major cost efficiency programme announced in November 2021. The costs recognised primarily relate to professional fees incurred and redundancy provisions. Whilst the costs incurred this year do not meet the quantitative threshold to be classified as exceptional on a standalone basis, when taken in aggregate with the costs expected to be incurred over the duration of the programme, we have concluded that the costs should be classified as exceptional in line with our exceptional items policy. The total cash outflow for the period was £48 million. Transaction and separation costs £223 million of transaction and separation costs were incurred in the period in relation to the acquisition of WPD (see note 37), the planned disposal of NECO (see note 10) and the planned disposal of our UK Gas Transmission business (see note 10). The costs relate to legal fees, bankers’ fees and other professional fees. The costs have been classified as exceptional, consistent with similar costs for the year ended 31 March 2021. The total cash outflow for the year was £196 million. Environmental insurance recovery In the US, the most significant component of our £1.9 billion environmental provision relates to several Superfund sites, and arose from former manufacturing gas plant facilities, previously owned or operated by the Group or its predecessor companies. Under Federal and State Superfund laws, potential liability for the historical contamination may be imposed on responsible parties jointly and severally, without regard to fault, even if the activities were lawful when they occurred. In the year, we have recognised an exceptional gain of £38 million relating to an insurance receivable for site remediation costs that are included in our Superfund sites environmental provision. The insurance receipts have been recorded as an exceptional item in line with the treatment of the related costs. 2021 New operating model implementation costs The Group incurred £50 million of costs in relation to the design and implementation of our new operating model that is built on a foundation of six business units. The costs recognised in the year ended 31 March 2021 primarily related to professional fees incurred and redundancy provisions. In evaluating the costs incurred against the quantitative thresholds in our exceptional items framework we considered the total costs to be incurred over the duration of the programme. Whilst the costs incurred did not meet the quantitative threshold to be classified as exceptional on a standalone basis, we concluded that the costs should be classified as exceptional in line with our exceptional items policy, in order to ensure that the costs are treated in a consistent manner with similar costs incurred previously. The total cash outflow for the year was £33 million. Transaction and separation costs £24 million of transaction and separation costs were incurred in relation to the acquisition of WPD (see note 37) and the planned sale of NECO (see note 10). The costs related to legal fees, bankers’ fees and professional fees. Whilst the costs incurred in isolation were not sufficiently material to warrant classification as an exceptional item, we expected further costs to be incurred in the next year, for example, in regard to success fees on completion of the acquisition. When taken in aggregate, the costs incurred over both years will be sufficiently material to be classified as exceptional in line with our policy. The total cash outflow for the year was £14 million. Changes in environmental provision We recognised an exceptional gain of £14 million relating to the release of environmental provisions relating to one of our US Superfund sites, for which the original provision was treated as an exceptional item. The reduction in the provision arose as a result of the re-evaluation of the Group’s share of estimated costs following the finalisation of discussions on the scope of certain remediation work with government authorities. The release was recorded as an exceptional item in line with the treatment of the original provision. 5. Exceptional items and remeasurements continued 2020 Changes in environmental provisions As a result of notices issued by governmental authorities and newly developed cost estimates prepared by third-party engineers in relation to our US Superfund sites, we re-evaluated our estimates of total costs and cost sharing allocations borne by the Company, and accordingly increased our provision by £326 million. Under the terms of our rate plans, we are entitled to recovery of environmental clean‑up costs from rate payers, but under IFRS no asset can be recognised for this recovery. Also included in the total environmental charge was the £74 million (re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation) impact of the change in the real discount rate applied to the environmental provisions across the Group, of which £66 million related to the US and £8 million to the UK. Given the substantial and sustained change in gilts and corporate bond yields, we concluded it was appropriate to reduce the real discount rate from 1% to 0.5%. The weighted average remaining duration of our cash flows is now around 10 years. Remeasurements Remeasurements comprise unrealised gains or losses recorded in the consolidated income statement arising from changes in the fair value of certain of our financial assets and liabilities accounted for at fair value through profit and loss (FVTPL). Once the fair value movements are realised (for example, when the derivative matures), the previously recognised fair value movements are then reversed through remeasurements and recognised within earnings before exceptional items and remeasurements. These assets and liabilities include commodity contract derivatives and financing derivatives to the extent that hedge accounting is not available or is not fully effective. The unrealised gains or losses reported in profit and loss on certain additional assets and liabilities treated at FVTPL are also classified within remeasurements. These relate to financial assets (which fail the ‘solely payments of principal and interest test’ under IFRS 9), the money market fund investments used by Group Treasury for cash management purposes and the net foreign exchange gains and losses on borrowing activities. These are offset by foreign exchange gains and losses on financing derivatives measured at fair value. In all cases, these fair values increase or decrease because of changes in foreign exchange, commodity or other financial indices over which we have no control. We report unrealised gains or losses relating to certain discrete classes of financial assets accounted for at FVTPL within adjusted profit. These comprise our portfolio of investments made by National Grid Partners, our investment in Sunrun Neptune 2016 LLC and the contingent consideration arising on the acquisition of National Grid Renewables (all within NGV and Other). The performance of these assets (including changes in fair value) is included in our assessment of adjusted profit for the relevant business units. Remeasurements excluded from adjusted profit are made up of the following categories: i. Net gains/(losses) on commodity contract derivatives represent mark-to-market movements on certain physical and financial commodity contract obligations in the US. These contracts primarily relate to the forward purchase of energy for supply to customers, or to the economic hedging thereof, that are required to be measured at fair value and that do not qualify for hedge accounting. Under the existing rate plans in the US, commodity costs are recoverable from customers although the timing of recovery may differ from the pattern of costs incurred; ii. Net gains/(losses) on financing derivatives comprise gains and losses arising on derivative financial instruments used for the risk management of interest rate and foreign exchange exposures. These exclude gains and losses for which hedge accounting has been effective, and have been recognised directly in the consolidated statement of other comprehensive income or are offset by adjustments to the carrying value of debt (see notes 17 and 32). Net foreign exchange gains and losses on financing derivatives used for the risk management of foreign exchange exposures are offset by foreign exchange losses and gains on borrowing activities; iii. Net gains/(losses) on financial assets measured at FVTPL comprise gains and losses on the investment funds held by our insurance captives which are categorised as FVTPL (see note 15); iv. Net gains/(losses) on financial liabilities measured at FVTPL comprise the change in the fair value (excluding changes due to own credit risk) of a financial liability that was designated at FVTPL on transition to IFRS 9 to reduce a measurement mismatch (see note 21); and v. Unrealised net gains/(losses) on derivatives and other financial instruments within our joint ventures and associates. Items included within tax 2022 Change in UK corporation tax rate In the Spring Budget 2021, the UK government announced that from 1 April 2023 the UK corporation tax rate will increase to 25%, and this was substantively enacted on 24 May 2021. Deferred tax balances at 31 March 2022 were remeasured at the enacted rate, with £458 million recognised as exceptional, in line with previous periods. 2020 The Finance Act 2016, which was enacted on 15 September 2016, reduced the main UK corporation tax rate to 17% with effect from 1 April 2020. Deferred tax balances were calculated at this rate for the years ended 31 March 2017 to 2019. On 17 March 2020, the UK government utilised the Provisional Collection of Taxes Act 1968 to substantively enact a reversal of the reduction in the main UK corporation tax rate to 17% with effect from 1 April 2020, resulting in the rate remaining at 19%. Deferred taxes at 31 March 2020 were measured using enacted tax rates and reflected in these financial statements, resulting in a £148 million deferred tax charge (re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation )

Finance income and costs

Finance income and costs	12 Months Ended
	Mar. 31, 2022
Analysis of income and expense [abstract]
Finance income and costs	6. Finance income and costs This note details the interest income generated by our financial assets and interest expense incurred on our financial liabilities, primarily our financing portfolio (including our financing derivatives). It also includes the net interest on our pensions and other post-retirement assets. In reporting adjusted profit, we adjust net financing costs to exclude any net gains or losses on financial instruments included in remeasurements (see note 5). Finance income and costs remeasurements include unrealised gains and losses on certain assets and liabilities now treated at FVTPL. The interest income, dividends and interest expense on these items are included in finance income and finance costs before remeasurements respectively. 2022 2021 1 2020 1 Notes £m £m £m Finance income Interest income on financial instruments: Bank deposits and other financial assets 32 33 48 Dividends received on equities held at fair value through other comprehensive income (FVOCI) 3 2 2 Other income 30 — 20 65 35 70 Finance costs Net interest on pensions and other post-retirement benefit obligations 25 — (51) (34) Interest expense on financial liabilities held at amortised cost: Bank loans and overdrafts (216) (53) (46) Other borrowings² (961) (741) (846) Interest on derivatives (59) (47) (92) Unwinding of discount on provisions 26 (73) (77) (75) Other interest 11 (51) (8) Less: interest capitalised³ 152 120 102 (1,146) (900) (999) Remeasurements – Finance income Net gains/(losses) on FVTPL financial assets (15) 23 (16) (15) 23 (16) Remeasurements – Finance costs Net gains/(losses) on financing derivatives 4 : Derivatives designated as hedges for hedge accounting 45 30 (14) Derivatives not designated as hedges for hedge accounting 29 17 (7) 74 47 (21) Total remeasurements – Finance income and costs 59 70 (37) Finance income 50 58 54 Finance costs 5 (1,072) (853) (1,020) Net finance costs from continuing operations (1,022) (795) (966) 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 2. Includes interest expense on lease liabilities (see note 13 for details). 3. Interest on funding attributable to assets in the course of construction in the current year was capitalised at a rate of 3.2% (2021: 3.1%; 2020: 3.6%). In the UK, capitalised interest qualifies for a current year tax deduction with tax relief claimed of £16 million (2021: £11 million; 2020: £15 million). In the US, capitalised interest is added to the cost of property, plant and equipment and qualifies for tax depreciation allowances. 4. Includes a net foreign exchange gain on borrowing activities of £110 million (2021: £73 million gain; 2020: £114 million gain) offset by foreign exchange losses and gains on financing derivatives measured at fair value.

Tax

Tax	12 Months Ended
	Mar. 31, 2022
Income Taxes [Abstract]
Tax	7. Tax Tax is payable in the territories where we operate, mainly the UK and the US. This note gives further details of the total tax charge and tax liabilities, including current and deferred tax. The current tax charge is the tax payable on this year’s taxable profits. Deferred tax is an accounting adjustment to provide for tax that is expected to arise in the future due to differences in the accounting and tax bases. The tax charge for the period is recognised in the income statement, the statement of comprehensive income or directly in the statement of changes in equity, according to the accounting treatment of the related transaction. The tax charge comprises both current and deferred tax. Current tax assets and liabilities are measured at the amounts expected to be recovered from or paid to the tax authorities. The tax rates and tax laws used to compute the amounts are those that have been enacted or substantively enacted by the reporting date. The Group operates internationally in territories with different and complex tax codes. Management exercises judgement in relation to the level of provision required for uncertain tax outcomes. There are a number of tax positions not yet agreed with the tax authorities where different interpretations of legislation could lead to a range of outcomes. Judgements are made for each position having regard to particular circumstances and advice obtained. Deferred tax is provided for using the balance sheet liability method, and is recognised on temporary differences between the carrying amount of assets and liabilities in the financial statements and the corresponding tax bases. Deferred tax liabilities are generally recognised on all taxable temporary differences, and deferred tax assets are recognised to the extent that it is probable that taxable profits will be available against which deductible temporary differences can be utilised. However, deferred tax assets and liabilities are not recognised if the temporary differences arise from the initial recognition of goodwill or from the initial recognition of other assets and liabilities in a transaction (other than a business combination) that affects neither the accounting nor the taxable profit or loss. Deferred tax liabilities are recognised on taxable temporary differences arising on investments in subsidiaries and joint arrangements except where the Company is able to control the reversal of the temporary difference and it is probable that the temporary difference will not reverse in the foreseeable future. Deferred tax is calculated at the tax rates that are expected to apply in the period when the liability is settled or the asset is realised, based on the tax rates and tax laws that have been enacted or substantively enacted by the reporting date. The carrying amount of deferred tax assets is reviewed at each reporting date and reduced to the extent that it is no longer probable that sufficient taxable profits will be available to allow all or part of the deferred tax asset to be recovered. Unrecognised deferred tax assets are reassessed at each reporting date and are recognised to the extent that it has become probable that future taxable profits will allow the deferred tax asset to be recovered. Deferred tax assets and liabilities are offset when there is a legally enforceable right to offset current tax assets against current tax liabilities and when they relate to income taxes levied by the same tax authority, and the Company and its subsidiaries intend to settle their current tax assets and liabilities on a net basis. 7. Tax continued The tax charge for the year can be analysed as follows: 2022 2021 1 2020 1 £m £m £m Current tax: UK corporation tax at 19% (2021: 19%; 2020: 19%) 255 157 132 UK corporation tax adjustment in respect of prior years (9) 15 5 246 172 137 Overseas corporation tax 6 3 (2) Overseas corporation tax adjustment in respect of prior years (26) (15) (41) (20) (12) (43) Total current tax from continuing operations 226 160 94 Deferred tax: UK deferred tax 605 39 207 UK deferred tax adjustment in respect of prior years (5) (20) (4) 600 19 203 Overseas deferred tax 425 174 64 Overseas deferred tax adjustment in respect of prior years 7 7 9 432 181 73 Total deferred tax from continuing operations 1,032 200 276 Total tax charge from continuing operations 1,258 360 370 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. Tax charged/(credited) to the consolidated statement of comprehensive income and equity 2022 2021 1 2020 1 £m £m £m Current tax: Cash flow hedges, cost of hedging and own credit reserve — — — Deferred tax: Investments at fair value through other comprehensive income — 12 (1) Cash flow hedges, cost of hedging and own credit reserve (12) 6 (38) Remeasurements of pension assets and post-retirement benefit obligations 493 462 (226) Share-based payments (4) 1 (2) 477 481 (267) Total tax recognised in the statements of comprehensive income from continuing operations 481 480 (265) Total tax relating to share-based payments recognised directly in equity from continuing operations (4) 1 (2) 477 481 (267) 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 7. Tax continued The tax charge for the year, for the continuing business, is higher (2021: higher tax charge; 2020: lower tax charge) than the standard rate of corporation tax in the UK of 19% (2021: 19%; 2020: 19%): 2022 2021 1 2020 1 £m £m £m Profit before tax from continuing operations Before exceptional items and remeasurements 2,880 1,628 1,963 Exceptional items and remeasurements 561 36 (563) Profit before tax from continuing operations 3,441 1,664 1,400 Profit before tax from continuing operations multiplied by UK corporation tax rate of 19% (2021: 19%; 2020: 19%) 654 316 266 Effect of: Adjustments in respect of prior years² (33) (12) (31) Expenses not deductible for tax purposes 47 29 24 Non-taxable income³ (49) (7) (18) Adjustment in respect of foreign tax rates⁴ 170 42 18 Deferred tax impact of change in UK tax rate 501 — 148 Adjustment in respect of post-tax profits of joint ventures and associates included within profit before tax (17) (12) (17) Other 5 (15) 4 (20) Total tax charge from continuing operations 1,258 360 370 % % % Effective tax rate – continuing operations 36.6 21.6 26.4 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 2. The prior year adjustments are primarily due to agreement of prior period tax returns. 3. Includes tax on chargeable disposals after the offset of capital losses and tax on the profits deferred to the following accounting period. 4. Includes remeasurement of US closing State deferred tax balances as a result of expected increase in the blended State tax rate following the disposal of NECO. 5. Other primarily comprises the movement in the deferred tax asset on previously unrecognised capital losses, claims for land remediation relief and impact of fair value movements on capitalised hedging. Factors that may affect future tax charges In the Spring Budget 2021, the UK government announced an increase in the main corporation tax rate from 19% to 25% with effect from 1 April 2023. This was substantively enacted on 24 May 2021. Deferred tax balances as at 31 March 2022, that are expected to reverse after 1 April 2023, have been calculated at 25%. The US government continues to consider changes to federal tax legislation, but as no changes have been substantively enacted at the balance sheet date, deferred tax balances as at 31 March 2022 have been calculated at the prevailing tax rates based on the current tax laws. We will continue to monitor the developments driven by Brexit, the OECD’s Base Erosion and Profit Shifting (BEPS) project and European Commission initiatives including fiscal aid investigations. At this time, we do not expect this to have any material impact on our future tax charges. Governments across the world including the UK and the US have introduced various stimulus/reliefs for businesses to cope with the impact of the COVID-19 pandemic, from which we do not currently expect there to be a material impact on our future tax charges. 7. Tax continued Tax included within the statement of financial position The following are the major deferred tax assets and liabilities recognised, and the movements thereon, during the current and prior reporting periods: Regulatory licences Accelerated Share- Pensions Financial Other net differences 1 £m Total Deferred tax liabilities/(assets) At 1 April 2020 — 6,562 (48) (360) (55) (1,653) 4,446 Exchange adjustments and other 2 — (501) 4 51 4 174 (268) Charged/(credited) to income statement — 373 — (12) 1 (147) 215 Charged to other comprehensive income and equity — — 2 414 6 — 422 At 1 April 2021 — 6,434 (42) 93 (44) (1,626) 4,815 Exchange adjustments and other 2 — 247 (1) 1 1 (85) 163 Charged/(credited) to income statement — 1,050 26 118 153 (117) 1,230 Charged/(credited) to other comprehensive income and equity — — (6) 587 (10) — 571 Reclassification to held for sale (note 10) — (643) 5 (166) 2 (1) (803) Acquisition of WPD (note 37) 429 622 — 142 (403) (1) 789 At 31 March 2022 429 7,710 (18) 775 (301) (1,830) 6,765 1. The deferred tax asset of £1,830 million as at 31 March 2022 (2021: £1,626 million) in respect of other net temporary differences primarily relates to net operating losses of £428 million (2021: £455 million), US environmental provisions of £511 million (2021: £453 million) and US bad debt provision of £201 million (2021: £184 million). 2. Exchange adjustments and other primarily comprises foreign exchange arising on translation of the US dollar deferred tax balances. Deferred tax assets and liabilities are only offset where there is a legally enforceable right of offset and there is an intention to settle the balances net. The deferred tax balances (after offset) for statement of financial position purposes consist solely of deferred tax liabilities of £6,765 million (2021: £4,815 million). This balance is after offset of a deferred tax asset of £428 million (2021: £455 million) which has been recognised in respect of net operating losses (£418 million) and capital losses (£10 million). Deferred tax assets in respect of some capital losses as well as trading losses and non-trade deficits have not been recognised as their future recovery is uncertain or not currently anticipated. The total deferred tax assets not recognised are as follows: 2022 2021 £m £m Capital losses 2,363 1,620 Non-trade deficits 1 1 Trading losses 7 7 The capital losses arose in the UK on disposal of certain businesses or assets. They are available to carry forward indefinitely but can only be offset against future capital gains. The UK non-trade deficits arose prior to 1 April 2017 and therefore can only be offset against future non-trade profits.

Earnings per share (EPS)

Earnings per share (EPS)	12 Months Ended
	Mar. 31, 2022
Earnings per share [abstract]
Earnings per share (EPS)	8. Earnings per share (EPS) EPS is the amount of profit after tax attributable to each ordinary share. Basic EPS is calculated on profit after tax for the year attributable to equity shareholders divided by the weighted average number of shares in issue during the year. Diluted EPS shows what the impact would be if all outstanding share options were exercised and treated as ordinary shares at year end. The weighted average number of shares is increased by additional shares issued as scrip dividends and reduced by shares repurchased by the Company during the year. The earnings per share calculations are based on profit after tax attributable to equity shareholders of the Company which excludes non-controlling interests. Adjusted earnings and EPS, which exclude exceptional items and remeasurements, are provided to reflect the adjusted profit sub-totals used by the Company. We have included reconciliations from this additional EPS measure to earnings for both basic and diluted EPS to provide additional detail for these items. For further details of exceptional items and remeasurements, see note 5. (a) Basic EPS Earnings EPS Earnings EPS Earnings EPS 2022 2022 2021 1 2021 1 2020 1 2020 1 £m pence £m pence £m pence Adjusted earnings from continuing operations 2,210 61.4 1,293 36.7 1,600 46.2 Exceptional items and remeasurements after tax from continuing operations (see note 5) (28) (0.8) 10 0.3 (571) (16.5) Earnings from continuing operations 2,182 60.6 1,303 37.0 1,029 29.7 Adjusted earnings from discontinued operations (see note 10) 344 9.6 340 9.7 317 9.2 Exceptional items and remeasurements after tax from discontinued operations (173) (4.8) (3) (0.1) (82) (2.4) Earnings from discontinued operations 171 4.8 337 9.6 235 6.8 Total adjusted earnings 2,554 71.0 1,633 46.4 1,917 55.4 Total exceptional items and remeasurements after tax (including discontinued operations) (201) (5.6) 7 0.2 (653) (18.9) Total earnings 2,353 65.4 1,640 46.6 1,264 36.5 2022 2021 2020 millions millions millions Weighted average number of ordinary shares – basic 3,599 3,523 3,461 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. (b) Diluted EPS Earnings EPS Earnings EPS Earnings EPS 2022 2022 2021 1 2021 1 2020 1 2020 1 £m pence £m pence £m pence Adjusted earnings from continuing operations 2,210 61.1 1,293 36.5 1,600 46.0 Exceptional items and remeasurements after tax from continuing operations (see note 5) (28) (0.8) 10 0.3 (571) (16.4) Earnings from continuing operations 2,182 60.3 1,303 36.8 1,029 29.6 Adjusted earnings from discontinued operations 344 9.5 340 9.6 317 9.1 Exceptional items and remeasurements after tax from discontinued operations (see note 10) (173) (4.8) (3) (0.1) (82) (2.4) Earnings from discontinued operations 171 4.7 337 9.5 235 6.7 Total adjusted earnings 2,554 70.6 1,633 46.1 1,917 55.1 Total exceptional items and remeasurements after tax (including discontinued operations) (201) (5.6) 7 0.2 (653) (18.8) Total earnings 2,353 65.0 1,640 46.3 1,264 36.3 2022 2021 2020 millions millions millions Weighted average number of ordinary shares – diluted 3,616 3,540 3,478 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. (c) Reconciliation of basic to diluted average number of shares 2022 2021 2020 millions millions millions Weighted average number of ordinary shares – basic 3,599 3,523 3,461 Effect of dilutive potential ordinary shares – employee share plans 17 17 17 Weighted average number of ordinary shares – diluted 3,616 3,540 3,478

Dividends

Dividends	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Dividends	9. Dividends Interim dividends are recognised when they become payable to the Company’s shareholders. Final dividends are recognised when they are approved by shareholders. 2022 2021 2020 Pence Cash Scrip dividend Pence per share Cash Scrip dividend £m Pence per share Cash Scrip dividend £m Interim dividend in respect of the current year 17.21 339 282 17.00 348 249 16.57 335 241 Final dividend in respect of the prior year 32.16 583 562 32.00 1,065 54 31.26 557 517 49.37 922 844 49.00 1,413 303 47.83 892 758

Assets held for sale and discon

Assets held for sale and discontinued operations	12 Months Ended
	Mar. 31, 2022
Non-current Assets Held For Sale And Discontinued Operations [Abstract]
Assets held for sale and discontinued operations	10. Assets held for sale and discontinued operations The results and cash flows of significant assets or businesses sold during the year are shown separately from our continuing operations, and presented within discontinued operations in the income statement and cash flow statement. Assets and businesses are classified as held for sale when their carrying amounts are recovered through sale rather than through continuing use. They only meet the held for sale condition when the assets are ready for immediate sale in their present condition, management is committed to the sale and it is highly probable that the sale will complete within one year. Depreciation ceases on assets and businesses when they are classified as held for sale and the assets and businesses are impaired if the proceeds less sale costs fall short of the carrying value. (a) Assets held for sale The following assets and liabilities were classified as held for sale as at 31 March 2022: Total assets Total liabilities held for sale Net assets held for sale The Narragansett Electric Company 4,129 (1,658) 2,471 UK Gas Transmission 5,871 (5,530) 341 Net assets held for sale 10,000 (7,188) 2,812 The Narragansett Electric Company On 17 March 2021, the Group signed an agreement to sell 100% of the share capital of a wholly owned subsidiary, NECO. NECO is part of our New England segment and is a retail distribution company providing electricity and gas to customers in Rhode Island. The associated assets and liabilities were consequently presented as held for sale in the consolidated financial statements for the year ended 31 March 2021. As NECO does not represent a separate major line of business or geographical operations, the criteria for classification as a discontinued operation are not met and accordingly its results have not been separately disclosed on the face of the income statement. Whilst all of the regulatory approvals are in place, the disposal of NECO was not finalised as at 31 March 2022 due to the appeal of one of these approvals by the Rhode Island Attorney General. The following assets and liabilities of NECO were classified as held for sale at 31 March 2022: £m Goodwill 590 Intangible assets 4 Property, plant and equipment 3,173 Trade and other receivables 251 Cash and cash equivalents 6 Other assets 105 Total assets held for sale 4,129 Borrowings (1,177) Pension liabilities (12) Other liabilities (469) Total liabilities held for sale (1,658) Net assets held for sale 2,471 No impairment losses were recognised upon remeasurement of the assets and liabilities prior to classification as held for sale. NECO generated profit after tax of £237 million for the year ended 31 March 2022 (2021: £104 million; 2020: £31 million). Current and deferred tax balances relating to NECO have not been included as held for sale on the basis that those balances will be retained by National Grid rather than transferred with the other assets and liabilities of NECO. Furthermore, the tax balances of NECO have been classified within current and non-current assets and liabilities with the corresponding offsets from the other Group members in accordance with the jurisdictional netting principles. 10. Assets held for sale and discontinued operations continued (a) Assets held for sale continued UK Gas Transmission The Group announced its intention to sell the UK Gas Transmission business on 18 March 2021. On 27 March 2022, the Group agreed to sell 100% of the UK Gas Transmission business to a new entity (the ‘Acquiring Entity’) in exchange for £4.2 billion cash consideration (subject to customary completion adjustments) and a 40% interest in the Acquiring Entity. The other 60% in the Acquiring Entity will be owned by Macquarie Infrastructure and Real Assets (MIRA) and British Columbia Investment Management Corporation (BCI) (together, the ‘Consortium’). £2.0 billion of the cash consideration comes from additional debt financing raised by the Acquiring Entity at completion. The sale is expected to complete in the third quarter of the financial year ending 31 March 2023 subject to the receipt of all regulatory approvals. On 27 March 2022, the Group also entered into a Further Acquisition Agreement (FAA) with the Consortium. This allows the Consortium to purchase the Group’s 40% interest in the Acquiring Entity for £1.4 billion plus an annualised escalation factor. The FAA can be exercised either in the period between 1 January and 31 March 2023 or in the period between 1 April and 30 June 2023. The deferral of the option window is at our discretion (subject to change, depending on the timing of the closing of the sale agreement). The Group classified the associated assets and liabilities of the business as held for sale in the consolidated statement of financial position as at 31 August 2021, when the sale was considered to be highly probable following management approval of the sale timetable and communication thereof to potential buyers. As at 31 March 2022, the following assets and liabilities of the UK Gas Transmission business were classified as held for sale: £m Intangible assets 159 Property, plant and equipment 4,719 Trade and other receivables 215 Pension assets 664 Cash and cash equivalents 9 Financing derivatives 93 Other assets 12 Total assets held for sale 5,871 Borrowings (4,165) Deferred tax liabilities (803) Other liabilities (562) Total liabilities held for sale (5,530) Net assets held for sale 341 No impairment losses were recognised upon remeasurement of the assets and liabilities prior to classification as held for sale. (b) Discontinued operations Planned disposal of UK Gas Transmission As UK Gas Transmission represents a major separate line of business, the business has also met the criteria for classification as a discontinued operation, and therefore the results of the business have been shown separately from the continuing business for all periods presented on the face of the income statement as a discontinued operation. Disposal of Quadgas HoldCo Limited In June 2019, the Group sold its remaining 39% interest in Cadent (held through its holding in Quadgas HoldCo Limited (Quadgas)). The aggregate carrying value of our investment in Quadgas at the disposal date was £1,956 million and the total sales proceeds were £1,965 million, resulting in a gain on disposal of £9 million. We considered the disposal of our 39% investment in Quadgas as the final stage of the plan to dispose of our interest in the UK Gas Distribution business first announced in 2015, and accordingly treated the results and cash flows arising from Quadgas as a discontinued operation on the basis that the sale formed the final part of a ‘single coordinated plan’ to dispose of UK Gas Distribution. 10. Assets held for sale and discontinued operations continued (b) Discontinued operations continued The summary income statements for UK Gas Transmission and Quadgas, together representing the discontinued operations of the Group, for the years ended 31 March 2022, 2021 and 2020 are as follows: 2022 2021 2020 £m £m £m Discontinued operations Revenue 1,362 1,114 1,180 Other operating costs (725) (620) (702) Operating profit 637 494 478 Finance income — — 6 Finance costs 1 (230) (75) (147) Profit before tax 407 419 337 Tax 2 (236) (82) (111) Profit after tax from discontinued operations 171 337 226 Gain on disposal — — 9 Total profit after tax from discontinued operations 171 337 235 1. Finance costs from discontinued operations include principal accretion of inflation linked liabilities in the UK Gas Transmission business of £158 million (2021: £38 million; 2020: £76 million). 2. Of the £236 million tax charge in the year ended 31 March 2022, £145 million relates to deferred tax due to the change in the UK corporation tax rate. The summary statement of comprehensive income for discontinued operations for the years ended 31 March 2022, 2021 and 2020 are as follows: 2022 2021 2020 £m £m £m Profit after tax from discontinued operations 171 337 235 Other comprehensive income/(loss) from discontinued operations Items from discontinued operations that will never be reclassified to profit or loss: Remeasurement gains/(losses) on pension assets and post-retirement benefit obligations 309 (250) 58 Net losses on financial liability designated at fair value through profit and loss attributable to changes in own credit risk (1) (11) (3) Net losses in respect of cash flow hedging of capital expenditure — (2) — Tax on items that will never be reclassified to profit or loss (94) 50 (20) Total gains/(losses) from discontinued operations that will never be reclassified to profit or loss 214 (213) 35 Items from discontinued operations that may be reclassified subsequently to profit or loss: Net gains/(losses) in respect of cash flow hedges 1 3 (1) Net (losses)/gains in respect of cost of hedging (4) (6) 2 Tax on items that may be reclassified subsequently to profit or loss — — 2 Total losses from discontinued operations that may be reclassified subsequently to profit or loss (3) (3) 3 Other comprehensive income/(loss) for the year, net of tax from discontinued operations 211 (216) 38 Total comprehensive income for the year from discontinued operations 382 121 273 Details of the cash flows relating to discontinued operations are set within the consolidated cash flow statement.

Goodwill

Goodwill	12 Months Ended
	Mar. 31, 2022
Intangible Assets [Abstract]
Goodwill	11. Goodwill Goodwill represents the excess of what we paid to acquire businesses over the fair value of their net assets at the acquisition date. We assess whether goodwill is recoverable by performing an impairment review annually or more frequently if events or changes in circumstances indicate a potential impairment. Goodwill and fair value adjustments arising on the acquisition of a foreign entity are treated as assets and liabilities of the foreign entity and translated at the closing exchange rate. Goodwill is allocated to cash-generating units (CGUs) and this allocation is made to those CGUs that are expected to benefit from the acquisition in which the goodwill arose. Impairment is recognised where there is a difference between the carrying value of the CGU and the estimated recoverable amount of the CGU to which that goodwill has been allocated. Any impairment is recognised immediately in the income statement and is not subsequently reversed. Any impairment loss is first allocated to the carrying value of the goodwill and then to the other assets within the CGU. Recoverable amount is defined as the higher of fair value less costs to sell and estimated value-in-use at the date the impairment review is undertaken. Value-in-use represents the present value of expected future cash flows, discounted using a pre-tax discount rate that reflects current market assessments of the time value of money and the risks specific to the asset for which the estimates of future cash flows have not been adjusted. Total £m Net book value at 1 April 2020 5,712 Exchange adjustments (562) Reclassification to held for sale (note 10) (562) Net book value at 1 April 2021 4,588 Exchange adjustments 223 Acquisition of WPD (note 37) 4,721 Net book value at 31 March 2022 9,532 There was no significant accumulated impairment charge as at 31 March 2022 or 31 March 2021. Following the announcement of the planned sale of NECO (see note 10), goodwill balances relating to our Rhode Island CGU and a portion of the goodwill relating to our previously reported Federal CGU were reclassified as held for sale in the prior period. Following the implementation of our new operating model during the year ended 31 March 2022, we have reassessed our CGUs. The Federal CGU (£544 million) is now allocated across the New York, New England and National Grid Ventures Renewables CGUs. The Massachusetts CGU (£963 million) is now allocated to the New England CGU. These changes reflect the updated level at which goodwill is now monitored for internal management purposes. Impairment review of goodwill and indefinite-lived intangibles Goodwill and indefinite-lived intangibles (see note 12) are reviewed annually for impairment and the recoverability is assessed by comparing the carrying amount of our operations with the expected recoverable amount on a value-in-use basis which uses pre-financing and pre-tax cash flow projections based on the Group’s financial plans, approved by the Directors, as a starting point. See below for a summary of which operations our goodwill and indefinite-lived intangibles are allocated to: 2022 CGU or group of CGUs £m Goodwill: National Grid Ventures Renewables 150 New England 1,510 New York 3,151 WPD 1 4,721 Total goodwill 9,532 Indefinite-lived intangibles (regulatory licences related to WPD): West Midlands 518 East Midlands 519 South Wales 257 South West 420 Total indefinite-lived intangibles 1,714 1. This is a combination of the West Midlands, East Midlands, South Wales and South West CGUs, reflecting the level at which the goodwill is monitored. In each assessment, the value-in-use has been calculated assuming a stable regulatory framework and is based on projections that incorporate our best estimates of future cash flows, including costs, changes in commodity prices, future rates and growth. Such projections reflect our current regulatory agreements, taking into account regulatory arrangements to allow for future agreements and recovery of investment, including those related to achieving the net zero plans of the jurisdictions that we operate in. Our plans have proved to be reliable guides in the past and the Directors believe the estimates are appropriate. 11. Goodwill continued (a) Cash flow periods, terminal value and discount rate assumptions We select cash flow durations longer than five years, when our forecasts are considered reliable. The cash flow durations selected reflect our knowledge and understanding of the regulatory environments in which we operate, and most significantly, where markets have legislated decarbonisation commitments by 2050, we utilise longer cash flow forecasts that reflect the investment required to deliver those commitments before applying a terminal value at the point those commitments are due to be fulfilled and market growth is expected to stabilise. For our regulated WPD operations, we consider cash flow durations that run until 2050, reflecting the expected investment required in the network, in excess of economy‑wide long-term growth rates in order to deliver the energy transition. For our regulated US operations (New York and New England CGUs), we use a five-year cash flow forecast. For our WPD business, a nominal terminal growth rate of 2.5% is assumed upon the terminal year cash flows, reflecting management’s best view, based on market and operational experience, of the expected long-term growth in the relevant market. For our US regulated operations, due to differences in the regulatory framework and the combination of gas and electricity networks, we apply a growth rate of 2.25%. This has been determined with regard to data on industry growth projections, specifically related to the energy transition, and projected growth in real gross domestic product (GDP) for the territory within which the CGU is based. Pre-tax cash flows are discounted by applying a pre-tax discount rate reflecting the time value of money and the risks specific to the group of assets. In practice, the post-tax discount rate for the group of assets in question is taken as a starting point, before considering industry peer discount rates to apply adjustments, as required, ensuring the rate applied is independent of the entity’s capital structure and to reflect a market participants’ view of a risk adjusted discount rate specific to the CGU or group of CGUs. The post-tax discount rate is then grossed up to a pre-tax discount rate that is applied to pre-tax cash flows. The pre-tax discount rates used for the year ended 31 March 2022 were as follows: WPD Group 5.2%; WPD DNOs 4.9%; New York 5.5%; and New England 5.6%. The discount rate and terminal growth rate applied in the year ended 31 March 2021 to the CGUs assessed at that date were 5.3% and 2.1% respectively. (b) Key inputs and sensitivity analysis In assessing the carrying value of goodwill and licences, we have sensitised our forecasts to factor in adjustments to key inputs to each model. Whilst regulatory licences are tested for impairment before we test goodwill, we consider the sensitivity for all balances separately for WPD and our regulated US operations below. WPD goodwill We identified the discount rate and the terminal growth rate as key assumptions for which the value-in-use calculation is the most sensitive in our impairment review. A reduction in the terminal growth rate to 2% resulted in WPD’s carrying amount equalling its recoverable amount. Considering the sensitivity to the discount rate applied, we found that increasing the pre-tax discount rate by 0.2% (to 5.4%) will result in WPD’s carrying amount equalling its recoverable amount (see notes 1 and 35). WPD indefinite-lived regulatory licences No reasonable changes to inputs to the impairment test performed over the South West, East Midlands, West Midlands and South Wales Distribution Network Operator CGUs were identified as resulting in an impairment. Regulated US operations: New York and New England goodwill While it is possible that a key assumption in the calculation could change, the Directors believe that no reasonably foreseeable change would result in an impairment of goodwill, in view of the long-term nature of the key assumptions and the margin by which the estimated value-in-use exceeds the carrying amount. This remains the case even after taking into account the short-term effects of COVID-19 and inflationary pressures, the most significant of which is an increase in bad debt charges in the short term, but not a risk of impairment to goodwill.

Other intangible assets

Other intangible assets	12 Months Ended
	Mar. 31, 2022
Intangible Assets [Abstract]
Other intangible assets	12. Other intangible assets Other intangible assets include software which is written down (amortised) over the period we expect to receive a benefit from the asset. An amortisation expense is charged to the income statement to reflect the reduced value of the asset over time. Amortisation is calculated by estimating the number of years we expect the asset to be used (useful economic life or UEL) and charging the cost of the asset to the income statement equally over this period. Indefinite-lived intangibles comprise regulatory licences for which there is no foreseeable limit to the period over which they are expected to generate net cash inflows. These assets are considered to have an indefinite life and are not amortised but subject to a review for impairment annually, or more frequently if events or circumstances indicate a potential impairment. Any impairment is charged to the income statement as it arises. Identifiable intangible assets are recorded at cost less accumulated amortisation and any provision for impairment, with the exception of regulatory licences that are assessed to have indefinite lives and are therefore tested annually for impairment (see note 11 for details of impairment tests performed over indefinite-lived intangible assets). Other intangible assets are tested for impairment only if there is an indication that the carrying value of the assets may have been impaired. Impairments of assets are calculated as the difference between the carrying value of the asset and the recoverable amount, if lower. Where such an asset does not generate cash flows that are independent from other assets, the recoverable amount of the CGU to which that asset belongs is estimated. Impairments are recognised in the consolidated income statement within Other operating income and costs. Any assets which suffered impairment in a previous period are reviewed for possible reversal of the impairment at each reporting date. The Group’s regulatory licences relate to electricity distribution licences acquired in connection with the Group’s acquisition of WPD on 14 June 2021 (see note 37). The licences provide the right to operate and invest in the relevant network that operates as a monopoly in the licensed geographic area. Once granted by Ofgem, the licence is issued to a licensee on the basis that it remains active into perpetuity. On that basis, the value attributed to the electricity distribution network licence assets is considered to have an indefinite useful life. Internally generated intangible assets, such as software, are recognised only if: i) an asset is created that can be identified; ii) it is probable that the asset created will generate future economic benefits; and iii) the development cost of the asset can be measured reliably. Where no internally generated intangible asset can be recognised, development expenditure is recorded as an expense in the period in which it is incurred. Cloud computing arrangements are reviewed to determine if the Group has control of the software intangible asset. Control is considered to exist where the Group has the right to take possession of the software and run it on its own or a third party’s computer infrastructure or if the Group has exclusive rights to use the software such that the supplier is unable to make the software available to other customers. Costs relating to configuring or customising the software in a cloud computing arrangement are assessed to determine if there is a separate intangible asset over which the Group has control. If an asset is identified, it is capitalised and amortised over the useful economic life of the asset. To the extent that no separate intangible asset is identified, then the costs are either expensed when incurred or recognised as a prepayment and spread over the term of the arrangement if the costs are concluded to not be distinct. The accounting for costs incurred in cloud computing arrangements represents the application of new accounting guidance for the Group for the year ended 31 March 2022. Certain costs which were previously capitalised in respect of the Group’s cloud computing arrangements have been expensed in the period. 12. Other intangible assets continued Other than regulatory licences, intangible assets are amortised on a straight-line basis over their estimated useful economic lives. Amortisation periods for other intangible assets are: Years Software 3 to 10 Regulatory licences Indefinite Regulatory licences 1 £m Software £m Assets in the course of construction Total Cost at 1 April 2020 — 2,026 557 2,583 Exchange adjustments — (102) (43) (145) Additions — 7 414 421 Disposals — (47) (2) (49) Reclassifications 2 — 255 (240) 15 Reclassification to held for sale (note 10) — (19) — (19) Cost at 1 April 2021 — 2,120 686 2,806 Exchange adjustments — 69 11 80 Additions — 15 513 528 Acquisition of WPD (note 37) 1,714 49 — 1,763 Disposals — (7) — (7) Reclassifications 2 — 260 (302) (42) Reclassification to held for sale (note 10) — (431) (38) (469) Cost at 31 March 2022 1,714 2,075 870 4,659 Accumulated amortisation at 1 April 2020 — (1,288) — (1,288) Exchange adjustments — 61 — 61 Amortisation charge for the year — (196) — (196) Accumulated amortisation of disposals — 44 — 44 Reclassification to held for sale (note 10) — 16 — 16 Accumulated amortisation at 1 April 2021 — (1,363) — (1,363) Exchange adjustments — (33) — (33) Amortisation charge for the year — (297) — (297) Impairment³ — — (10) (10) Accumulated amortisation of disposals — 7 — 7 Reclassification to held for sale (note 10) — 309 — 309 Accumulated amortisation at 31 March 2022 — (1,377) (10) (1,387) Net book value at 31 March 2022⁴ 1,714 698 860 3,272 Net book value at 31 March 2021 — 757 686 1,443 1. Relates to the licence intangibles acquired as part of the acquisition of WPD (see note 37). The Group assesses its indefinite-life intangible assets for impairment annually (see note 11). 2. Reclassifications includes amounts transferred to property, plant and equipment (see note 13). 3. Depreciation of assets in the course of construction relates to impairment provision adjustments recognised in the year. 4. The Group has capitalised £366 million (2021: £298 million) in relation to the Gas Business Enablement system in the US, of which £152 million (2021: £82 million) is in service and is being amortised over 10 years, with the remainder included within assets in the course of construction. A further £103 million (2021: £nil) in relation to our new UK general ledger system was reclassified from assets in the course of construction to software assets in the period to 31 March 2022, and is now amortised over 10 years.

Property, plant and equipment

Property, plant and equipment	12 Months Ended
	Mar. 31, 2022
Property, plant and equipment [abstract]
Property, plant and equipment	13. Property, plant and equipment Property, plant and equipment are the physical assets controlled by us. The cost of these assets primarily represents the amount initially paid for them or the fair value on the date of acquisition of a business. Cost includes both their purchase price and the construction and other costs associated with getting them ready for operation. A depreciation expense is charged to the income statement to reflect annual wear and tear and the reduced value of the asset over time. Depreciation is calculated by estimating the number of years we expect the asset to be used (useful economic life or UEL) and charging the cost of the asset to the income statement equally over this period. We operate an energy networks business and therefore have a significant physical asset base. We continue to invest in our networks to maintain reliability, create new customer connections and ensure our networks are flexible and resilient. Our business plan envisages these additional investments will be funded through a mixture of cash generated from operations and the issue of new debt. Property, plant and equipment is recorded at cost, less accumulated depreciation and any impairment losses. Cost includes the purchase price of the asset; any payroll and finance costs incurred which are directly attributable to the construction of property, plant and equipment together with an appropriate portion of overheads which are directly linked to the capital work performed; and the cost of any associated asset retirement obligations. Property, plant and equipment includes assets in which the Group’s interest comprises legally protected statutory or contractual rights of use. Additions represent the purchase or construction of new assets, including capital expenditure for safety and environmental assets, and extensions to, enhancements to, or replacement of, existing assets. All costs associated with projects or activities which have not been fully commissioned at the period end are classified within assets in the course of construction. Items within property, plant and equipment are tested for impairment only if there is some indication that the carrying value of the assets may have been impaired. Impairments of assets are calculated as the difference between the carrying value of the asset and the recoverable amount, if lower. Where such an asset does not generate cash flows that are independent from other assets, the recoverable amount of the cash-generating unit to which that asset belongs is estimated. Impairments are recognised in the income statement and if immaterial are included within the depreciation charge for the year. (a) Analysis of property, plant and equipment Land and buildings £m Plant and machinery £m Assets Motor vehicles and office equipment £m Total £m Cost at 1 April 2020 3,897 59,609 4,771 1,036 69,313 Exchange adjustments (213) (3,308) (130) (73) (3,724) Additions 89 328 4,023 70 4,510 Disposals (6) (344) (26) (48) (424) Reclassifications¹ 96 3,007 (3,243) 77 (63) Reclassification to held for sale (note 10) (111) (3,231) (174) (44) (3,560) Cost at 1 April 2021 3,752 56,061 5,221 1,018 66,052 Exchange adjustments 97 1,627 111 37 1,872 Additions 22 926 4,843 129 5,920 Acquisition of WPD (note 37) 200 9,512 185 154 10,051 Disposals (165) (367) — (88) (620) Reclassifications¹ 62 4,063 (4,133) 89 81 Reclassification to held for sale (note 10) (309) (8,800) (640) (267) (10,016) Cost at 31 March 2022 3,659 63,022 5,587 1,072 73,340 Accumulated depreciation at 1 April 2020 (847) (18,042) — (662) (19,551) Exchange adjustments 37 698 — 46 781 Depreciation charge for the year (90) (1,270) — (116) (1,476) Disposals — 339 — 48 387 Reclassifications¹ 2 (5) — 6 3 Reclassification to held for sale (note 10) 22 798 — 27 847 Accumulated depreciation at 1 April 2021 (876) (17,482) — (651) (19,009) Exchange adjustments (20) (351) — (23) (394) Depreciation charge for the year² (114) (1,300) (48) (167) (1,629) Disposals 29 311 — 88 428 Reclassifications¹ 15 (40) (18) 2 (41) Reclassification to held for sale (note 10) 193 4,421 6 217 4,837 Accumulated depreciation at 31 March 2022 (773) (14,441) (60) (534) (15,808) Net book value at 31 March 2022 2,886 48,581 5,527 538 57,532 Net book value at 31 March 2021 2,876 38,579 5,221 367 47,043 1. Represents amounts transferred between categories, (to)/from other intangible assets (see note 12), from inventories and reclassifications between cost and accumulated depreciation. 2. Depreciation of assets in the course of construction relates to impairment provision adjustments recognised in the year. 13. Property, plant and equipment continued (a) Analysis of property, plant and equipment continued 2022 2021 £m £m Information in relation to property, plant and equipment Capitalised interest included within cost 2,114 2,233 Contributions to cost of property, plant and equipment included within: Trade and other payables 137 138 Non-current liabilities 421 400 Contract liabilities – current 130 66 Contract liabilities – non-current 1,342 1,094 (b) Asset useful economic lives No depreciation is provided on freehold land or assets in the course of construction. Other items of property, plant and equipment are depreciated, on a straight-line basis, at rates estimated to write off their book values over their estimated useful economic lives. In assessing estimated useful economic lives, consideration is given to any contractual arrangements and operational requirements relating to particular assets. The assessments of estimated useful economic lives and residual values of assets are performed annually. Unless otherwise determined by operational requirements, the depreciation periods for the principal categories of property, plant and equipment are, in general, as shown in the table below split between the UK and US, along with the weighted average remaining UEL for each class of property, plant and equipment (which is calculated by applying the annual depreciation charge per class of asset to the net book value of that class of asset). Years UK US Weighted average remaining UEL¹ Freehold and leasehold buildings up to 60 up to 100 41 Plant and machinery: Electricity transmission plant and wires up to 100 45 to 80 31 Electricity distribution plant 3 to 99 35 to 85 45 Electricity generation plant n/a 20 to 93 12 Interconnector plant and other 5 to 60 5 to 50 32 Gas plant – mains, services and regulating equipment n/a 47 to 80 55 Gas plant – storage 5 to 40 12 to 65 12 Gas plant – meters 7 to 30 14 to 40 24 Motor vehicles and office equipment up to 30 up to 26 5 1. Excluded from the above table are depreciation periods in respect of items of property, plant and equipment which are classified as held for sale as at 31 March 2022. (c) Gas asset lives The role that gas networks play in the pathway to achieving the greenhouse gas emissions reductions targets set in the jurisdictions in which we operate is currently uncertain. However, we believe the gas assets which we own and operate today will continue to have a crucial role in maintaining security, reliability and affordability of energy beyond 2050, although the scale and purpose for which the networks will be used is dependent on technological developments and policy choices of governments and regulators. With respect to our US gas distribution assets, asset lives are assessed as part of detailed depreciation studies completed as part of each separate rate proceeding. Depreciation studies consider the physical condition of assets and the expected operational life of an asset. We believe these assessments are our best estimate of the UEL of our gas network assets in the US. The weighted average remaining UEL for our US gas distribution fixed asset base is circa 58 years, however a sizeable proportion of our assets are assumed to have UELs which extend beyond 2080. We continue to believe the lives identified by rate proceedings are the best estimate of the assets’ UELs, although we continue to keep this assumption under review as we learn more about possible future pathways towards net zero. Whilst the targets, goals and ambitions have now been formalised in legislation in the states in which we operate, there is widespread recognition that work needs to be done to define the possible future decarbonisation pathways. We continue to actively engage and support our regulators to enable the clean energy transition in a safe, reliable and affordable way. Asset depreciation lives feed directly into our US regulatory recovery mechanisms, such that any shortening of asset lives and regulatory recovery periods as agreed with regulators should be recoverable through future rates, subject to agreement, over future periods, as part of wider considerations around ensuring the continuing affordability of gas in our service territories. Given the uncertainty described relating to the UELs of our gas assets, below we provide a sensitivity on the depreciation charge for our New York and New England segments were a shorter UEL presumed: Increase in depreciation expense for the year ended 31 March 2022 Increase in depreciation expense for the year ended 31 March 2021 1 New York New England New York New England UELs limited to 2050 140 40 125 35 UELs limited to 2060 67 15 57 13 UELs limited to 2070 31 1 26 2 1. Comparative amounts have been re-presented to reflect the new operating segments and the classification of the UK Gas Transmission business as a discontinued operation. See notes 1, 2 and 10 for further information. 13. Property, plant and equipment continued (c) Gas asset lives continued Note that this sensitivity calculation excludes any assumptions regarding the residual value for our asset base and the effect that shortening asset depreciation lives would be expected to have on our regulatory recovery mechanisms. In the event that any of the US gas distribution assets are stranded, the Group would expect to recover the associated costs. While recovery is not guaranteed and is determined by regulators in the US, there are precedents for stranded asset cost recovery for US utility companies. (d) Right-of-use assets The Group leases various properties, land, equipment and cars. New lease arrangements entered into are recognised as a right-of-use asset and a corresponding liability at the date at which the leased asset is available for use by the Group. The right-of-use asset and associated lease liability arising from a lease are initially measured at the present value of the lease payments expected over the lease term. The lease payments include fixed payments, any variable lease payments dependent on an index or a rate, and any break fees or renewal option costs that we are reasonably certain to incur. The discount rate applied is the rate implicit in the lease or, if that is not available, then the incremental rate of borrowing for a similar term and similar security (which is determined based on observable data for borrowing rates for the specific group entity that has entered into the lease, with specific adjustments for the term of the lease and any lease-specific risk premium). The lease term takes account of exercising any extension options that are at our option if we are reasonably certain to exercise the option and any lease termination options unless we are reasonably certain not to exercise the option. Each lease payment is allocated between the liability and finance cost. The finance cost is charged to the income statement over the lease period using the effective interest rate method. The right-of-use asset is depreciated over the shorter of the asset’s useful life and the lease term on a straight-line basis. For short-term leases (lease term of 12 months or less) and leases of low-value assets (such as computers), the Group continues to recognise a lease expense on a straight-line basis. The table below shows the movements in the net book value of right-of-use assets included within property, plant and equipment at 31 March 2022 and 31 March 2021, split by category. The associated lease liabilities are disclosed in note 21. Land and Plant and Assets Motor Total Net book value at 1 April 2020 364 95 — 225 684 Exchange adjustments (30) (4) — (22) (56) Additions 60 6 — 64 130 Reclassifications — — — (15) (15) Depreciation charge for the year (29) (16) — (68) (113) Net book value at 31 March 2021 365 81 — 184 630 Exchange adjustments 10 1 — 10 21 Additions 14 2 — 88 104 Acquisition of WPD (note 37) 7 2 — — 9 Reclassification to held for sale (note 10) (7) — — (4) (11) Modifications of leases¹ (122) — — — (122) Disposals (2) — — (1) (3) Depreciation charge for the year (40) (16) — (67) (123) Net book value at 31 March 2022 225 70 — 210 505 1. The Group entered into an agreement to reduce the lease term of its New England corporate office, Reservoir Woods, with effect from October 2021. The existing lease liability and right-of-use asset have been remeasured based on the terms of the modified lease. The following balances have been included in the income statement for the years ended 31 March 2022 and 31 March 2021 in respect of right-of-use assets: 2022 2021 £m £m Included within net finance income and costs: Interest expense on lease liabilities (18) (21) Included within revenue: Lease income¹ 385 390 Included within operating expenses: Expense relating to short-term and low-value leases (14) (13) 1. Included within lease income is £374 million (2021: £376 million) of variable lease payments, the majority of which relates to the power supply arrangement entered into with LIPA (see note 3). The total of future minimum sublease payments expected to be received under non-cancellable subleases is £108 million (2021: £104 million).

Other non-current assets

Other non-current assets	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Other non-current assets	14. Other non-current assets Other non-current assets include assets that do not fall into any other non-current asset category (such as goodwill or property, plant and equipment) where the benefit to be received from the asset is not due to be received until after 31 March 2023. 2022 2021 £m £m Other receivables 110 45 Non-current tax assets 6 6 Prepayments — 5 Accrued income¹ 187 237 303 293

Financial and other investments

Financial and other investments	12 Months Ended
	Mar. 31, 2022
Disclosure of financial assets [abstract]
Financial and other investments	15. Financial and other investments The Group holds a range of financial and other investments. These investments include short-term money market funds, quoted investments in equities or bonds of other companies, investments in our venture capital portfolio (National Grid Partners), bank deposits with a maturity of greater than three months, and investments that can not be readily used in operations, principally collateral deposited in relation to derivatives. The classification of each investment held by the Group is determined based on two main factors: • its contractual cash flows – whether the assets cash flows are solely payments of the principal and interest on the financial asset on pre-determined dates or whether the cash flows are determined by other factors such as the performance of a company; and • the business model for holding the investments – whether the intention is to hold onto the investment for the longer term (collect the contractual cash flows), or to sell the asset with the intention of managing any gain or loss on sale or to manage any liquidity requirements. The four categories of financial and other investments are as follows: • Financial assets at amortised cost – debt instruments that have contractual cash flows that are solely payments of principal and interest, and which are held within a business model whose objective is to collect contractual cash flows, are held at amortised cost. This category includes our receivables in relation to deposits and collateral; • FVOCI debt and other investments – debt investments, such as bonds, that have contractual cash flows that are solely payments of principal and interest, and which are held within a business model whose objective is both to collect the contractual cash flows and to sell the debt instruments, are measured at fair value through other comprehensive income (FVOCI), with gains or losses recognised in the consolidated statement of comprehensive income instead of through the income statement. On disposal, any gains or losses are recognised within finance income in the income statement (see note 6). Other investments include insurance contracts, measured at fair value, and held to back the present value of unfunded pension liabilities in note 25; • FVOCI equity instruments – the Group previously held equity instruments which it elected to measure at FVOCI on the basis that they were not held for trading and so the recognition of any gains and losses on these investments in the income statement would not have been representative of performance. The shares were held as part of a portfolio of financial instruments which back some long-term employee liabilities. In the year ended 31 March 2022, the Group sold all of the remaining equities as part of a plan to de-risk that investment portfolio. The fair value of the equities on the date of sale was £111 million and upon disposal realised gains and losses of £82 million were transferred to retained earnings (see note 28); and • FVTPL investments – other financial investments are subsequently measured at fair value with any gains or losses recognised in the income statement (FVTPL). This primarily comprises our money market funds, insurance company fund investments and corporate venture capital investments held by National Grid Partners. Financial and other investments are initially recognised on trade date. Subsequent to initial recognition, the fair values of financial assets that are quoted in active markets are based on bid prices. When independent prices are not available, fair values are determined using valuation techniques used by the relevant markets using observable market data where possible (see note 32(g) for further details). 15. Financial and other investments continued 2022 2021 £m £m Non-current FVOCI debt and other investments 413 416 FVOCI equity investments¹ — 99 FVTPL investments 417 240 830 755 Current FVTPL investments 2,292 1,768 Financial assets at amortised cost 853 574 3,145 2,342 3,975 3,097 Financial and other investments include the following: Investments in short-term money market funds 1,936 1,412 Investments held by National Grid Partners 309 136 Investments in Sunrun 109 103 Balances that are restricted or not readily used in operations: Collateral 2 806 540 Insurance company and non-qualified plan investments 534 589 Cash surrender value of life insurance policies 234 283 Other investments 47 34 3,975 3,097 1. In the year ended 31 March 2022, the Group sold its equity investments which were previously held in relation to non-qualified pension plans in the US. 2. The collateral balance includes £802 million (2021: £480 million) of collateral placed with counterparties with whom we have entered into a credit support annex to the International Swaps and Derivatives Association (ISDA) Master Agreement and £4 million (2021: £18 million) of restricted amounts allocated for specific projects within the National Grid Electricity System Operator. In the year ended 31 March 2021, £42 million of the balance included collateral paid by operating companies as security deposits. In the current year this collateral has been replaced with letters of credit as permitted under the Connection and Use of System Code. FVTPL and FVOCI investments are recorded at fair value. The carrying value of current financial assets at amortised cost approximates their fair values, primarily due to short-dated maturities. The exposure to credit risk at the reporting date is the fair value of the financial investments. For further information on our credit risk, refer to note 32(a). For the purposes of impairment assessment, the investments in bonds are considered to be low risk as they are investment grade securities; life insurance policies are held with regulated insurance companies; and deposits, collateral receivable and other financial assets at amortised cost are investment grade. All financial assets held at FVOCI or amortised cost are therefore considered to have low credit risk and have an immaterial impairment loss allowance equal to 12-month expected credit losses. In determining the expected credit losses for these assets, some or all of the following information has been considered: credit ratings, the financial position of counterparties, the future prospects of the relevant industries and general economic forecasts. No FVOCI or amortised cost financial assets have had modified cash flows during the period. There has been no change in the estimation techniques or significant assumptions made during the year in assessing the loss allowance for these financial assets. There were no significant movements in the gross carrying value of financial assets during the year that contribute to changes in the loss allowance. No collateral is held in respect of any of the financial investments in the above table. No balances are more than 30 days past due, and no balances were written off during the year.

Investments in joint ventures a

Investments in joint ventures and associates	12 Months Ended
	Mar. 31, 2022
Interests In Other Entities [Abstract]
Investments in joint ventures and associates	16. Investments in joint ventures and associates Investments in joint ventures and associates represent businesses we do not control but over which we exercise joint control or significant influence. They are accounted for using the equity method. A joint venture is an arrangement established to engage in economic activity, which the Group jointly controls with other parties and has rights to a share of the net assets of the arrangement. An associate is an entity which is neither a subsidiary nor a joint venture, but over which the Group has significant influence. 2022 2021 Associates Joint Total Associates £m Joint ventures £m Total £m Share of net assets at 1 April 229 638 867 341 654 995 Exchange adjustments 6 19 25 (22) (36) (58) Additions 17 469 486 6 75 81 Share of post-tax results for the year 43 49 92 30 28 58 Share of other comprehensive income of associates, net of tax 1 — 1 1 — 1 Dividends received (35) (123) (158) (31) (49) (80) Disposals — (50) (50) — — — Other movements¹ 16 (41) (25) (96) (34) (130) Share of net assets at 31 March 277 961 1,238 229 638 867 1. Other movements relate to tax liabilities for US and certain UK associates and joint ventures which are borne by the Group and the elimination of profits arising from sales to the Group’s share of joint ventures. Within associates, the other movements in the year ended 31 March 2021 primarily relates to the reclassification of the Group’s investment in Sunrun from an investment in an associate to financial investments. A list of joint ventures and associates including the name and proportion of ownership is provided in note 34. Transactions with and outstanding balances with joint ventures and associates are shown in note 31. The joint ventures and associates have no significant contingent liabilities to which the Group is exposed, and the Group has no significant contingent liabilities in relation to its interests in the joint ventures and associates. The Group has capital commitments of £714 million (2021: £141 million) in relation to joint ventures and associates. On 15 March 2022, the Group disposed of its entire 50% interest in St William Homes LLP to The Berkeley Group for cash consideration of £413 million. The receipt of cash has been recognised within net cash used in investing activities within the cash flow statement. The Group recognised a gain on disposal of £228 million within Other operating income and costs and released to revenue deferred income of £189 million which related to deferred profits related to previous property sales to St William Homes LLP. The gain on disposal and the release of deferred income are both classified as exceptional in the year (see note 5). The following table describes the Group’s material joint ventures and associates at 31 March 2022: Joint venture % stake BritNed Development Limited 1 50 % BritNed is a joint venture with the Dutch transmission system operator, TenneT, and operates the subsea electricity link between Great Britain and the Netherlands, commissioned in 2011. Nemo Link Limited 1 50 % Nemo is a joint venture with the Belgian transmission operator, Elia, and is a subsea electricity interconnector between Great Britain and Belgium, which became operational on 31 January 2019. Emerald Energy Venture LLC 51 % Emerald is a joint venture with Washington State Investment Board and builds and operates wind and solar assets. Emerald was acquired on 11 July 2019. Bight Wind Holdings LLC 27.3 % Bight Wind is a joint venture with RWE Renewables. Following the successful win at auction of six seabed leases in northeastern US on 25 February 2022, Bight Wind will commence the development of an offshore wind project which will play a key role in supplying clean energy to customers in New York. At 31 March 2022, the Group has an amount payable to Bight Wind of £223 million in respect of a capital call to the Group which is payable in April 2022. The assets, liabilities and results of Bight Wind will become material to the Group upon recognition of the seabed lease in the year ending 31 March 2023. Material associate % stake Millennium Pipeline Company LLC 26.25 % Millennium Pipeline Company LLC is an associate that owns a natural gas pipeline from southern New York to the Lower Hudson Valley. 1. BritNed and Nemo have reporting periods ending on 31 December with monthly management reporting information provided to National Grid. 16. Investments in joint ventures and associates continued Summarised financial information as at 31 March, together with the carrying amount of material investments, is as follows: BritNed Development Nemo Link Limited Emerald Energy Millennium Pipeline Company LLC 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Statement of financial position Non-current assets 390 409 515 536 1,070 559 800 795 Cash and cash equivalents 77 47 7 31 134 112 33 27 All other current assets 10 24 7 8 8 12 29 24 Non-current liabilities (52) (50) (34) (30) (182) (182) (237) (256) Non-current financial liabilities (29) (31) — — (310) (104) — — Current liabilities (15) (22) (33) (19) (66) (25) (45) (38) Current financial liabilities — — — — (23) (2) — — Net assets 381 377 462 526 631 370 580 552 Group’s ownership interest 191 189 231 263 322 189 152 145 Group adjustment: elimination — — — — (49) (23) — — Carrying amount of the Group’s investment 191 189 231 263 273 166 152 145 BritNed Development Nemo Link Limited Emerald Energy Millennium Pipeline Company LLC 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Income statement Revenue 131 72 148 66 25 28 200 199 Depreciation and amortisation (15) (15) (23) (24) (17) (14) (43) (43) Other costs (9) (15) (6) (6) (145) (22) (20) (21) Operating profit/(loss) 107 42 119 36 (137) (8) 137 135 Net interest expense (2) (1) (1) — (5) — (21) (18) Profit/(loss) before tax 105 41 118 36 (142) (8) 116 117 Income tax expense (20) (11) (22) (14) — — — — Profit/(loss) for the year 85 30 96 22 (142) (8) 116 117 Group’s share of profit/(loss) 43 15 48 11 (72) (4) 30 31 Group adjustment: tax credit/(charge) — — — — 19 1 (8) (9) Group’s share of post-tax results for the year 43 15 48 11 (53) (3) 22 22 While we present consolidated results in these financial statements as if we were one company, our legal structure is such that there are a number of different operating and holding companies that contribute to the overall result. This structure has evolved through acquisitions as well as regulatory requirements to have certain activities within separate legal entities. Subsidiary undertakings A list of the Group’s subsidiaries as at 31 March 2022 is given below. The entire share capital of subsidiaries is held within the Group except where the Group’s ownership percentages are shown. These percentages give the Group’s ultimate interest and therefore allow for the situation where subsidiaries are owned by partly owned intermediate subsidiaries. Where subsidiaries have different classes of shares, this is largely for historical reasons, and the effective percentage holdings given represent both the Group’s voting rights and equity holding. Shares in National Grid (US) Holdings Limited, National Grid (US) Investments 2 Limited, National Grid Hong Kong Limited, National Grid Luxembourg SARL and NGG Finance plc are held directly by National Grid plc. All other holdings in subsidiaries are owned by other subsidiaries within the Group. All subsidiaries are consolidated in the Group’s financial statements. Principal Group companies are identified in bold . These companies are incorporated and principally operate in the countries under which they are shown. All entities incorporated in the United States are taxed in the United States on their worldwide income other than where indicated in the footnotes below. Other entities are tax resident in their jurisdiction of incorporation other than where indicated in the footnotes below. Incorporated in England and Wales Registered office: 1–3 Strand, London WC2N 5EH, UK (unless stated otherwise in footnotes). Birch Sites Limited Carbon Sentinel Limited Central Networks Trustees Limited 1 Droylsden Metering Services Limited Gridcom Limited Hyder Profit Sharing Trustees Limited 1 Icelink Interconnector Limited Kelston Properties 2 Limited 1 Lattice Group Employee Benefit Trust Limited Lattice Group Limited Lattice Group Trustees Limited Meter Operator Services Limited* 1 Meter Reading Services Limited* 1 Natgrid Limited NatGrid One Limited 2 NatgridTW1 Limited 2 National Grid (US) Holdings Limited 2 National Grid (US) Investments 2 Limited 2 National Grid (US) Investments 4 Limited 2 National Grid (US) Partner 1 Limited 2 National Grid Carbon Limited National Grid Commercial Holdings Limited National Grid Distributed Energy Limited National Grid Electricity Group Trustee Limited National Grid Electricity System Operator Limited National Grid Electricity Transmission plc National Grid Energy Metering Limited National Grid Gas Holdings Limited National Grid Gas plc National Grid Grain LNG Limited National Grid Holdings Limited 2 National Grid Holdings One plc National Grid Hydrogen Limited National Grid IFA 2 Limited National Grid Interconnector Holdings Limited National Grid Interconnectors Limited National Grid International Limited 2 National Grid Metering Limited National Grid North Sea Link Limited National Grid Offshore Limited National Grid Partners Limited National Grid Plus Limited National Grid Property Holdings Limited National Grid Smart Limited National Grid Ten National Grid Thirty Six Limited National Grid Twelve Limited 2 National Grid Twenty Eight Limited National Grid Twenty Seven Limited National Grid Twenty Three Limited 2 National Grid UK Limited National Grid UK Pension Services Limited National Grid Ventures Limited National Grid Viking Link Limited National Grid William Limited NG Nominees Limited NGC Employee Shares Trustee Limited NGG Finance plc Ngrid Intellectual Property Limited NGT Two Limited Port Greenwich Limited Sheet Road Management Company Limited (51%) 3 South Wales Electricity Share Scheme Trustees Limited 1 South Western Helicopters Limited 1 Supergrid Electricity Limited Supergrid Energy Transmission Limited Supergrid Limited Thamesport Interchange Limited The National Grid Group Quest Trustee Company Limited The National Grid YouPlan Trustee Limited Transco Limited Warwick Technology Park Management Company (No 2) Limited (60.56%) 4 Western Power Distribution (East Midlands) plc 1 Western Power Distribution (South Wales) plc 1 Western Power Distribution (South West) plc 1 Western Power Distribution (West Midlands) plc 1 Western Power Distribution Holding Company Limited 1 Western Power Distribution Investments Limited 1 Western Power Distribution plc 1 Western Power Generation Limited 1 Western Power Pension Trustee Limited 1 WPD Distribution Network Holdings Limited 1 WPD Investment Holdings limited 1 WPD Island Limited 1 WPD Limited 1 WPD Midlands Limited 1 WPD Midlands Networks Contracting Limited* 1 WPD Property Investments Limited 1 WPD Share Scheme Trustees Limited 1 WPD Smart Metering Limited 1 WPD Telecoms Limited 1 WPD WEM Holdings Limited 1 WPD WEM Limited 1 WW Share Scheme Trustees Limited 1 1. Registered office: Avonbank, Feeder Road, Bristol, Avon, BS2 0TB. 2. Companies where National Grid plc has issued guarantees over the liabilities of the companies as at 31 March 2022 and for which the companies are taking the exemption from the requirements of an audit for their individual financial statements as permitted by section 479A of the Companies Act. 3. Registered office: Netley Old Hall Farm, Dorrington, Shrewsbury, United Kingdom, SY5 7JY. 4. Registered office: Shire Hall, PO Box 9, Warwick CV34 4RL, UK. * In process of strike-off. Incorporated in the US Registered office: National Registered Agents, Inc., 1209 Orange Street, Wilmington, DE 19801, USA (unless stated otherwise in footnotes). Apple River Solar, LLC Armenia Solar, LLC Ashland Solar, LLC Athens Solar, LLC Autauga Solar, LLC Banner Solar, LLC Bazile Creek Wind Farm, LLC Bee Hollow Solar, LLC Bell Plaine Solar, LLC Benevolent Solar, LLC Blaze Solar, LLC 1 Blevins Solar, LLC Blue Ridge Wind, LLC Blue Spring Solar, LLC Blues Solar, LLC Bluewater Solar, LLC Boone Solar, LLC Boston Gas Company 2 Bridges Solar, LLC British Transco Capital, Inc. 3 British Transco Finance, Inc. 3 Brock Solar, LLC Broken Bridge Corp. 4 Brook Trout Solar, LLC Burley Solar, LLC Burlington Solar, LLC Burr Ridge Wind, LLC Cage Ranch Solar II, LLC Cage Ranch Solar III, LLC Cage Ranch Solar, LLC Caldwell Solar II, LLC Caldwell Solar, LLC Canby Solar, LLC Cass Wind Farm, LLC Cattle Ridge Wind Farm 2, LLC Cedar Grove Solar, LLC Centennial Solar, LLC Clay Boswell Solar, LLC Clear Creek Solar, LLC Clermont Solar, LLC Clinton County Solar, LLC Coles Solar, LLC Compass Prairie Wind, LLC Coneflower Solar, LLC 5 Conestoga Wind, LLC Copperhead Solar, LLC Creekview Solar, LLC Crocker Wind Farm 2, LLC Dahlia Solar, LLC 5 Dakota Hills Wind Farm, LLC Day Lily Solar, LLC 5 Deatsville Solar, LLC Deer Trail Solar, LLC Dodson Creek Solar, LLC 6 Donnellson Solar, LLC Elburn Solar, LLC Eldena Solar, LLC Elk Creek Solar 2, LLC Elk Creek Solar, LLC EUA Energy Investment Corporation 2 Exie Solar, LLC Falls City Solar, LLC Fayette Solar, LLC 7 Fillmore County Solar Project, LLC Firstview Wind Farm, LLC Fort Solar, LLC Front Range Wind Farm, LLC Gardenia Solar, LLC 5 Golden Solar, LLC Goldendale Solar, LLC Goldenrod Wind Farm, LLC Goldfinch Solar, LLC Grand Junction Solar, LLC Granite State Power Link LLC 3 Grant Solar 2, LLC Grant Solar, LLC Grayson Solar, LLC Greenbrier Creek Solar, LLC Greensky Solar, LLC Greenwood Solar, LLC Grid NY LLC 8 Grindstone Wind Farm, LLC 9 Hale County Solar, LLC Hansford Energy Storage, LLC Harmony Solar ND 2, LLC Harmony Solar ND, LLC Harrington Solar, LLC Hartley Solar, LLC Hearth Solar, LLC Hill River Solar, LLC Honeybee Solar, LLC Hoosier Solar, LLC Hoskins Solar, LLC Illumination Solar, LLC Innovation Solar, LLC Itasca Energy Development, LLC 5 Itasca Energy Services, LLC Jack Rabbit Wind, LLC Jackson County Solar, LLC Junction Solar, LLC KeySpan CI Midstream Limited 3 KeySpan Energy Corporation 8 KeySpan Energy Services Inc. 3 KeySpan Gas East Corporation 8 KeySpan International Corporation 3 KeySpan MHK, Inc. 3 KeySpan Midstream Inc. 3 KeySpan Plumbing Solutions, Inc. 8 Knox Solar, LLC KSI Contracting, LLC 3 KSI Electrical, LLC 3 KSI Mechanical, LLC 3 Lake Charlotte Solar, LLC Lake Iris Solar, LLC Lakeside Solar, LLC Land Management & Development, Inc. 8 Landwest, Inc. 8 Lansing Solar, LLC Leola Wind Farm, LLC Liberty Solar, LLC Lilac Solar, LLC 5 Livingston County Solar, LLC Long Mount Solar, LLC Lordsburg Solar, LLC Louisa Solar, LLC Lowlands Solar, LLC Lydia Solar, LLC Marion County Solar, LLC Massachusetts Electric Company 2 Maverick Wind Farm, LLC Meadowlands Solar, LLC Metrowest Realty LLC 3 Miller Creek Solar, LLC Millers Ferry Solar, LLC Morgan County Solar, LLC Morning Glory Solar, LLC 5 Muddy Creek Solar, LLC Mustang Ridge Wind Farm, LLC Mystic Steamship Corporation 6 Nantucket Electric Company 2 National Grid Development Holdings Corp. 3 National Grid Electric Services LLC 8 National Grid Energy Management LLC 3 National Grid Energy Services LLC 3 National Grid Energy Trading Services LLC 8 National Grid Engineering & Survey Inc. 8 National Grid Generation LLC 8 National Grid Generation Ventures LLC 8 National Grid Glenwood Energy Center, LLC 3 National Grid IGTS Corp. 8 National Grid Insurance USA Ltd 10 National Grid Islander East Pipeline LLC 3 National Grid LNG GP LLC 3 National Grid LNG LLC 3 National Grid LNG LP LLC 3 National Grid Millennium LLC 3 National Grid NE Holdings 2 LLC 2 National Grid North America Inc. 3 National Grid Partners Inc. 8 National Grid Partners LLC 3 National Grid Port Jefferson Energy Center LLC 3 National Grid Renewables Development, LLC National Grid Renewables E Wind, LLC 5 National Grid Renewables Operations, LLC 3 National Grid Renewables Projects, LLC 5 National Grid Renewables Stutsman, LLC National Grid Renewables, LLC 3 National Grid Services Inc. 3 National Grid US 6 LLC 3,† National Grid US LLC 3 National Grid USA Service Company, Inc. 2 National Grid USA 3 NEES Energy, Inc. 2 New England Electric Transmission Corporation 4 New England Energy Incorporated 2 New England Hydro Finance Company, Inc. (53.704%) 2 New England Hydro-Transmission Corporation (53.704%) 4 New England Hydro-Transmission Electric Company, Inc. (53.704%) 2 New England Power Company 2 Newport America Corporation 11 Newton Solar, LLC NG Renewables Energy Marketing, LLC 3 NG Renewables Energy Services, LLC NGNE LLC 3 NGV Emerald Energy Venture Holdings, LLC 3 NGV OSW Holdings, LLC 3 NGV US Distributed Energy Inc. 3 NGV US Transmission Inc. 3 NGV US, LLC 3 Niagara Mohawk Energy, Inc. 3 Niagara Mohawk Holdings, Inc. 8 Niagara Mohawk Power Corporation 8 Niobrara Wind, LLC NM Properties, Inc. 8 Noble Solar, LLC 12 Nordic VOS, LLC North East Transmission Co., Inc. 3 North Fork Wind, LLC Northeast Renewable Link LLC 3 Opinac North America, Inc. 3 Parklawn Solar, LLC Pennington Solar, LLC Peony Solar, LLC Philadelphia Coke Co., Inc. 3 Pierce County Solar, LLC Pike County Solar, LLC Pipestone Solar, LLC Plum Creek Wind Farm 2, LLC Plum Creek Wind Farm, LLC Port of the Islands North, LLC 8 Portage Solar, LLC Prairie Oasis Solar, LLC Prairie Rose Wind 2, LLC 5 Prosperity Wind Farm 2, LLC Prosperity Wind Farm, LLC Red Rock Solar SD, LLC Red Wolf Solar, LLC Regal Solar 2, LLC Regal Solar, LLC River North Solar, LLC Robertson Solar, LLC Rock Ridge Wind Farm, LLC Rolling Hills Solar, LLC Ross County Solar, LLC 6 Royal Solar 2, LLC Royal Solar, LLC Royerton Solar, LLC Saginaw Bay Solar, LLC Sandstone Creek Solar 2, LLC Sandstone Creek Solar, LLC Sapphire Sky Wind Farm, LLC Sherco Solar 2, LLC 5 Sherco Solar, LLC 5 Silver City Solar, LLC Simpson Solar, LLC Spotlight Solar, LLC Spring Brook Solar, LLC Spring River Solar, LLC Springfield Solar Farm, LLC Stony Brook Wind, LLC Stony Point Solar, LLC Stove Creek Solar, LLC Sturgis Solar, LLC Summit Lake Solar, LLC Sunbeam Solar, LLC Sunrise Solar, LLC Sycamore Creek Solar, LLC Thacker Solar, LLC The Brooklyn Union Gas Company 8 The Narragansett Electric Company 11 Torchlight Solar, LLC 5 Transgas Inc. 2 Tri-City Solar, LLC Uintah Solar, LLC Unbridled Solar, LLC Upper Hudson Development Inc. 8 Valley Solar, LLC Vermont Green Line Devco, LLC (90%) 3 Vibrant Solar, LLC Virgo Community Solar Gardens, LLC 5 Virtue Solar, LLC Vivid Solar, LLC Wallowa Solar, LLC Wayfinder Group, Inc. 2 Wheatfield Solar, LLC White Elm Wind Farm, LLC Wild Springs Solar, LLC 5 Wildcat Ridge Wind Farm, LLC Wildhorse Creek Solar, LLC Willard Solar, LLC Williams County Solar, LLC Wiregrass Solar, LLC Woodlands Solar, LLC Worthington Solar, LLC Yellowhammer Solar, LLC Young County Solar, LLC Incorporated in Australia Registered office: Level 7, 330 Collins Street, Melbourne, VIC 3000, Australia National Grid Australia Pty Limited Incorporated in Canada Registered office: Stewart McKelvey LLP, c/o Charles Reagh, Queen’s Marque, 600-1741 Lower Water Street, Halifax, Nova Scotia, B3J 0J2, Canada KeySpan Energy Development Co. Incorporated in Guernsey Registered office: 1st & 2nd Floors Elizabeth House, Les Ruettes Brayes, St Peter Port, GY1 1EW, Guernsey, Channel Islands WPD Limited (Guernsey) † Registered office: PO Box 155, Mill Court, La Charroterie, St. Peter Port, Guernsey, GY1 4ET, Guernsey, Channel Islands Aztec Insurance Limited Incorporated in Hong Kong Registered office: Level 54, Hopewell Centre, 183 Queen’s Road East, Hong Kong National Grid Hong Kong Limited † Incorporated in the Isle of Man Registered office: Third Floor, St George’s Court, Upper Church Street, Douglas, IM1 1EE, Isle of Man, UK National Grid Insurance Company (Isle of Man) Limited NGT Holding Company (Isle of Man) Limited* † Incorporated in Luxembourg Registered office: 412F, Route d’Esch, L-2086, Luxembourg, Grand Duchy of Luxembourg National Grid Luxembourg SARL Incorporated in the Netherlands Registered office: Westblaak 89, 3012 KG Rotterdam, PO Box 21153, 3001 AD, Rotterdam, Netherlands British Transco International Finance B.V. Incorporated in the Republic of Ireland Registered office: c/o Moore Stephens Nathans, Third Floor, Ulysses House, 23/24 Foley Street, Dublin, D01 W2T2, Ireland National Grid Company (Ireland) Designated Activity Company* 1. Registered office: National Registered Agents, Inc., 160 Greentree Drive, Suite 101, Dover DE 19904, USA. 2. Registered office: Corporation Service Company, 84 State Street, Boston MA 02109, USA. 3. Registered office: Corporation Service Company, 251 Little Falls Drive, Wilmington DE 19808, USA. 4. Registered office: Corporation Service Company, 10 Ferry Street, Suite 313, Concord NH 03301, USA. 5. Registered office: National Grid Renewables Development, LLC, 8400 Normandale Lake Blvd. Suite 1200, Bloomington, MN 55437, USA. 6. Registered office: The Corporation Trust Company, Corporation Trust Center, 1209 Orange Street, Wilmington, Delaware, 19801, USA. 7. Registered office: 60 Mine Lake Court, Suite 200, Raleigh, Wake County, NC 27615, USA. 8. Registered office: Corporation Service Company, 80 State Street, Albany NY 12207, USA. 9. Registered office: National Registered Agents, Inc., 30600 Telegraph Road, Suite 2345, Bingham Farms, MI 48025-5720, USA. 10. Registered office: One MetroTech Center, Brooklyn NY 11201, USA. 11. Registered office: Corporation Service Company, 222 Jefferson Boulevard, Suite 200, Warwick RI 02888, USA. 12. Registered office: National Registered Agents, Inc., 1999 Bryan Street, Dallas, Dallas County TX 75201, USA. * In liquidation. † Entity is tax resident in the United Kingdom. A list of the Group’s joint ventures as at 31 March 2022 is given below. All joint ventures are included in the Group’s financial statements using the equity method of accounting. Principal joint ventures are identified in bold . Incorporated in England and Wales Registered office: 1–3 Strand, London WC2N 5EH, UK (unless stated otherwise in footnotes). BritNed Development Limited (50%)* Joint Radio Company Limited (50%) 1 ** National Places LLP (50%) 2 Nemo Link Limited (50%) NGET/SPT Upgrades Limited (50%) † Incorporated in the US Registered office: Corporation Service Company, 251 Little Falls Drive, Wilmington, DE 19808, USA (unless stated otherwise in footnotes). Bight Wind Holdings, LLC (27.27%) 3 Clean Energy Storage Systems LLC (previously Clean Energy Generation, LLC) (50%) Emerald Energy Venture LLC (51%) Island Park Energy Center, LLC (50%) Islander East Pipeline Company, LLC (50%) 3 LI Energy Storage System, LLC (50%) LI Solar Generation, LLC (50%) Incorporated in France Registered office: 1 Terrasse Bellini, Tour Initiale, TSA 41000 – 9291, IFA2 (50%) A list of the Group’s associates as at 31 March 2022 is given below. Unless otherwise stated, all associates are included in the Group’s financial statements using the equity method of accounting. Principal associates are identified in bold . Incorporated in the US Registered office: Corporation Service Company, 251 Little Falls Drive, Wilmington, DE 19808, USA (unless stated otherwise in footnotes). Clean Line Energy Partners LLC (32%) 3 Connecticut Yankee Atomic Power Company (19.5%) 4 Direct Global Power, Inc. (26%) 3 Energy Impact Fund LP (9.41%) 5 KHB Venture LLC (33.33%) 6 Maine Yankee Atomic Power Company (24%) 7 Millennium Pipeline Company, LLC (26.25%) 3 New York Transco LLC (28.3%) 8 NYSEARCH RMLD, LLC (22.63%) The Hive IV, LLC (28.2%) 3 Yankee Atomic Electric Company (34.5%) 9 Incorporated in Belgium Registered office: Avenue de Cortenbergh 71, 1000 Brussels, Belgium Coreso SA (15.84%) Other investments A list of the Group’s other investments as at 31 March 2022 is given below. Incorporated in England and Wales Registered office: 1 More London Place, London SE1 2AF, UK Energis plc (33.06%)‡ Registered office: Third Floor, Northumberland House, 303–306 High Holborn, London, WC1V 7JZ Electralink Limited (27.04%) 1. Registered office: Friars House, Manor House Drive, Coventry, CV1 2TE, UK. 2. Registered office: 80 Cheapside, London, EC2V 6EE, UK. 3. Registered office: The Corporation Trust Company, Corporation Trust Center, 1209 Orange Street, Wilmington DE 19801, USA. 4. Registered office: Carla Pizzella, 362 Injun Hollow Road, East Hampton CT 06424-3099, USA. 5. Registered office: Harvard Business Services, Inc., 16192 Coastal Highway, Lewes DE 19958, USA. 6. Registered office: De Maximus Inc., 135 Beaver Street, 4th Floor, Waltham MA 02452, USA. 7. Registered office: Joseph D Fay, 321 Old Ferry Road, Wiscasset ME 04578, USA. 8. Registered office: Corporation Service Company, 80 State Street, Albany NY 12207, USA. 9. Registered office: Karen Sucharzewski, 49 Yankee Road, Rowe MA 01367, USA. * National Grid Interconnector Holdings Limited owns 284,500,000 €0.20 C Ordinary shares and one £1.00 Ordinary A share. ** National Grid Gas plc owns all £1.00 A Ordinary shares. † National Grid Electricity Transmission plc owns 50 £1.00 A Ordinary shares. ‡ In administration. Our interests and activities are held or operated through the subsidiaries, joint arrangements or associates as disclosed above. These interests and activities (and their branches) are established in – and subject to the laws and regulations of – these jurisdictions. The following UK subsidiaries will take advantage of the audit exemption set out within section 479A of the Companies Act 2006 supported by guarantees issued by National Grid plc over their liabilities for the year ended 31 March 2022: Company name Company number NatGrid One Limited 5521240 Natgrid TW1 Limited 7579324 National Grid Holdings Limited 3096772 National Grid International Limited 2537092 National Grid Twelve Limited 4355616 National Grid Twenty Three Limited 6999009 National Grid (US) Holdings Limited 2630496 National Grid (US) Investments 2 Limited 3784528 National Grid (US) Investments 4 Limited 3867128 National Grid (US) Partner 1 Limited 4314432

Derivative financial instrument

Derivative financial instruments	12 Months Ended
	Mar. 31, 2022
Financial Instruments [Abstract]
Derivative financial instruments	17. Derivative financial instruments Derivatives are financial instruments that derive their value from the price of an underlying item such as interest rates, foreign exchange rates, credit spreads, commodities, equities or other indices. In accordance with policies approved by the Board, derivatives are transacted generally to manage exposures to fluctuations in interest rates, foreign exchange rates and commodity prices. Our derivatives balances comprise two broad categories: • financing derivatives: These are used to manage our exposure to interest rates and foreign exchange rates. Specifically, we use these derivatives to manage our financing portfolio, holdings in foreign operations and contractual operational cash flows; and • commodity contract derivatives: These are used to manage our US customers’ exposure to price and supply risks. Some forward contracts for the purchase of commodities meet the definition of derivatives. We also enter into derivative financial instruments linked to commodity prices, including index futures, options and swaps, which are used to manage market price volatility. Derivatives are initially recognised at fair value and subsequently remeasured to fair value at each reporting date. Changes in fair values are recorded in the period they arise, in either the consolidated income statement or other comprehensive income. Where the gains or losses recorded in the income statement arise from changes in the fair value of derivatives to the extent that hedge accounting is not applied or is not fully effective, these are recorded as remeasurements, detailed in notes 5 and 6. Where the fair value of a derivative is positive it is carried as a derivative asset, and where negative as a derivative liability. The fair value of derivative financial instruments is calculated by taking the present value of future cash flows, primarily incorporating market observable inputs. The various inputs include foreign exchange spot and forward rates, yield curves of the respective currencies, currency basis spreads between the respective currencies, interest rate and inflation curves, the forward rate curves of underlying commodities, and for those positions that are not fully cash collateralised, the credit quality of the counterparties. Certain clauses embedded in non-derivative financial instruments or other contracts are presented as derivatives because they impact the risk profile of their host contracts and they are deemed to have risks or rewards not closely related to those host contracts. Further information on how derivatives are valued and used for risk management purposes is presented in note 32. Information on commodity contracts and other commitments not meeting the definition of derivatives is presented in note 30. The fair values of derivatives by category are as follows: 2022 2021 Assets Liabilities Total £m Assets £m Liabilities £m Total £m Current 282 (144) 138 457 (145) 312 Non-current 305 (869) (564) 542 (754) (212) 587 (1,013) (426) 999 (899) 100 Financing derivatives 298 (991) (693) 942 (767) 175 Commodity contract derivatives 289 (22) 267 57 (132) (75) 587 (1,013) (426) 999 (899) 100 (a) Financing derivatives The fair values of financing derivatives by type are as follows: 2022 2021 Assets Liabilities Total £m Assets £m Liabilities £m Total £m Interest rate swaps 89 (97) (8) 325 (159) 166 Cross-currency interest rate swaps 174 (642) (468) 601 (351) 250 Foreign exchange forward contracts¹ 35 (65) (30) 16 (74) (58) Inflation-linked swaps — (187) (187) — (183) (183) 298 (991) (693) 942 (767) 175 1. Included within the foreign exchange forward contracts balance are £21 million (2021: £32 million) of derivative liabilities in relation to the hedging of capital expenditure and a deal-contingent foreign exchange forward contract liability of £nil (2021: £9 million) in relation to the disposal of NECO (see note 10). 17. Derivative financial instruments continued (a) Financing derivatives continued The maturity profile of financing derivatives is as follows: 2022 2021 Assets Liabilities Total Assets £m Liabilities £m Total Current Less than 1 year 34 (136) (102) 428 (70) 358 34 (136) (102) 428 (70) 358 Non-current In 1 to 2 years 6 (29) (23) 10 (14) (4) In 2 to 3 years 28 (39) (11) 24 (12) 12 In 3 to 4 years — (26) (26) 62 (80) (18) In 4 to 5 years 12 (16) (4) 4 (42) (38) More than 5 years 218 (745) (527) 414 (549) (135) 264 (855) (591) 514 (697) (183) 298 (991) (693) 942 (767) 175 The notional contract amounts of financing derivatives by type are as follows: 2022 2021 £m £m Interest rate swaps (1,607) (2,259) Cross-currency interest rate swaps (10,397) (8,389) Foreign exchange forward contracts (6,371) (4,651) Inflation-linked swaps (500) (500) (18,875) (15,799) London Inter-bank Offered Rate (LIBOR) is being replaced as an interest rate benchmark by alternative reference rates and therefore we are transitioning LIBOR cash flows on our affected contracts in line with the relevant jurisdictions. During the year we transitioned derivatives which pay or receive cash flows that reference GBP LIBOR (maturing between 2023 and 2040) to alternative reference rates (not transitioned in 2021: £2,041 million, maturing between 2023 and 2026). Derivatives with a notional value of £806 million that reference USD LIBOR (maturing between 2023 and 2026) are yet to be amended (2021: £769 million, maturing between 2023 and 2026). (b) Commodity contract derivatives The fair values of commodity contract derivatives by type are as follows: 2022 2021 Assets Liabilities Total Assets Liabilities £m Total £m Commodity purchase contracts accounted for as derivative contracts Forward purchases of gas 11 (6) 5 44 (94) (50) Derivative financial instruments linked to commodity prices Electricity capacity 1 — 1 2 — 2 Electricity swaps 208 (10) 198 10 (33) (23) Electricity options 5 — 5 — (1) (1) Gas swaps 29 (6) 23 1 (3) (2) Gas options 35 — 35 — (1) (1) 289 (22) 267 57 (132) (75) 17. Derivative financial instruments continued (b) Commodity contract derivatives continued The maturity profile of commodity contract derivatives is as follows: 2022 2021 Assets Liabilities Total Assets £m Liabilities £m Total £m Current Less than one year 248 (8) 240 29 (75) (46) 248 (8) 240 29 (75) (46) Non-current In 1 to 2 years 34 (6) 28 7 (24) (17) In 2 to 3 years 5 (5) — 7 (16) (9) In 3 to 4 years 2 (2) — 7 (7) — In 4 to 5 years — (1) (1) 6 (5) 1 More than 5 years — — — 1 (5) (4) 41 (14) 27 28 (57) (29) 289 (22) 267 57 (132) (75) The notional quantities of commodity contract derivatives by type are as follows: 2022 2021 Forward purchases of gas 1 28m Dth 36m Dth Electricity swaps 13,458 GWh 12,321 GWh Gas swaps 39m Dth 47m Dth Gas options 59m Dth 40m Dth 1. Forward gas purchases have terms up to one year (2021: five years). The contractual obligations under these contracts are £86 million (2021: £104 million).

Inventories and current intangi

Inventories and current intangible assets	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Inventories and current intangible assets	18. Inventories and current intangible assets Inventories represent assets that we intend to use in order to generate revenue in the short term, either by selling the asset itself (for example, fuel stocks) or by using it to fulfil a service to a customer or to maintain our network (consumables). Inventories are stated at the lower of weighted average cost and net realisable value. Where applicable, cost comprises direct materials and direct labour costs as well as those overheads that have been incurred in bringing the inventories to their present location and condition. Emission allowances, principally relating to the emissions of carbon dioxide in the UK and sulphur and nitrous oxides in the US, are recorded as intangible assets within current assets. They are initially recorded at cost and subsequently at the lower of cost and net realisable value. A liability is recorded in respect of the obligation to deliver emission allowances, and emission charges are recognised in the income statement in the period in which emissions are made. 2022 2021 £m £m Fuel stocks 96 94 Raw materials and consumables 297 253 Current intangible assets – emission allowances 118 92 511 439 There is a provision for obsolescence of £7 million against inventories as at 31 March 2022 (2021: £10 million).

Trade and other receivables

Trade and other receivables	12 Months Ended
	Mar. 31, 2022
Trade and other receivables [abstract]
Trade and other receivables	19. Trade and other receivables Trade and other receivables include amounts which are due from our customers for services we have provided, accrued income which has not yet been billed, prepayments, contract assets where certain milestones are required to be fulfilled and other receivables that are expected to be settled within 12 months. Trade and other receivables are initially recognised at fair value and subsequently measured at amortised cost, less any appropriate allowances for estimated irrecoverable amounts. 2022 2021 £m £m Trade receivables 2,661 2,152 Accrued income 1,110 886 Provision for impairment of receivables and accrued income (741) (672) Trade receivables and accrued income, net 3,030 2,366 Prepayments 429 387 Contract assets 33 13 Other receivables 223 153 3,715 2,919 Trade receivables are non-interest-bearing and generally have an up to 60 days term. Due to their short maturities, the fair value of trade and other receivables approximates their carrying value. The maximum exposure of trade and other receivables to credit risk is the carrying amount reported on the balance sheet. Provision for impairment of receivables A provision for credit losses is recognised at an amount equal to the expected credit losses that will arise over the lifetime of the trade receivables and accrued income. 2022 2021 £m £m At 1 April 672 512 Exchange adjustments 31 (57) Charge for the year, net of recoveries 167 326 Uncollectible amounts written off (124) (59) Reclassification to held for sale (note 10) (5) (50) At 31 March 741 672 The trade receivables balance, accrued income balance and provisions balance split by geography are as follows: As at 31 March 2022 As at 31 March 2021 UK US Total UK US Total £m £m £m £m £m £m Trade receivables 352 2,309 2,661 227 1,925 2,152 Accrued income 715 395 1,110 547 339 886 Provision for impairment of receivables and accrued income (43) (698) (741) (23) (649) (672) 1,024 2,006 3,030 751 1,615 2,366 There are no retail customers in the UK businesses. A provision matrix is not used in the UK as an assessment of expected losses on individual debtors is performed, and the provision is not material. In the US, £2,243 million (2021: £1,852 million) of the trade receivables and accrued income balance is attributable to retail customers. For non-retail US customer receivables, a provision matrix is not used and expected losses are determined on individual debtors. The provision for retail customer receivables in the US is calculated based on a series of provision matrices which are prepared by regulated entity and by customer type. The expected loss rates in each provision matrix are based on historical loss rates adjusted for current and forecasted economic conditions at the balance sheet date. The inclusion of forward-looking information in the provision matrix setting process under IFRS 9 results in loss rates that reflect expected future economic conditions and the recognition of an expected loss on all debtors even where no loss event has occurred. In March 2020, the Group’s US distribution businesses ceased certain customer cash collection activities in response to regulatory instructions and to changes in State, Federal and City level regulations and guidance, and actions to minimise risk to the Group’s employees as a result of COVID-19. At that time, the Group also ceased customer termination activities as requested by relevant local authorities. Collection and customer termination activities resumed in New England during the year ended 31 March 2022, where permitted. Whilst certain collection activities also resumed in New York in the year, we expect to resume full collection activities over the course of the next year. Collection activities have also been supported by certain government COVID funding programmes in both New England and New York. In calculating our provision for impairment of receivables at 31 March 2022, we were able to incorporate the actual cash collection levels experienced for the two years since the start of the pandemic to determine the expected loss rates per category of outstanding receivable by operating company, which is summarised in the provision matrix shown below. Factored into our analysis are expected cash collections based on the resumed collection activities in New England and New York during the year. 19. Trade and other receivables continued Based on our review, we recognised a charge of £139 million which represents our best estimate based on the information available. For the year ended 31 March 2021, we recognised a charge of £325 million due to the ongoing reduction of customer terminations and collections which were ceased in the preceding year and not fully recovered as at 31 March 2022. We based our review of certain macroeconomic factors at the time, including unemployment levels and our experience regarding debtor recoverability during and in the aftermath of the 2008/09 financial crisis. The average expected loss rates and gross balances for the retail customer receivables in our US operations are set out below: 2022 2021 % £m % £m Accrued income 5 382 7 322 0 – 30 days past due 5 731 7 580 30 – 60 days past due 20 213 24 155 60 – 90 days past due 32 123 36 108 3 – 6 months past due 41 161 52 140 6 – 12 months past due 56 177 66 180 Over 12 months past due 71 456 71 367 2,243 1,852 US retail customer receivables are not collateralised. Trade receivables are written off when regulatory requirements are met. Write-off policies vary between jurisdictions as they are aligned with the local regulatory requirements, which differ between regulators. There were no significant amounts written off during the period that were still subject to enforcement action. Our internal definition of default is aligned with that of the individual regulators in each jurisdiction.

Cash and cash equivalents

Cash and cash equivalents	12 Months Ended
	Mar. 31, 2022
Cash and cash equivalents [abstract]
Cash and cash equivalents	20. Cash and cash equivalents Cash and cash equivalents include cash balances, together with short-term investments with an original maturity of less than three months that are readily convertible to cash. Net cash and cash equivalents reflected in the cash flow statement are net of bank overdrafts, which are reported in borrowings. The carrying amounts of cash and cash equivalents and bank overdrafts approximate their fair values. Cash at bank earns interest at floating rates based on daily bank deposit rates. Short-term deposits are made for periods varying between one day and three months, depending on the immediate cash requirements, and earn interest at the respective short-term deposit rates. Cash and cash equivalents held in currencies other than sterling have been converted into sterling at year-end exchange rates. For further information on currency exposures, refer to note 32(c). Cash and cash equivalents at 31 March 2022 include £14 million (2021: £12 million) that is restricted. The restricted cash balances include amounts required to be maintained for insurance purposes and cash balances that can only be used for low-carbon network fund projects. 2022 2021 £m £m Cash at bank 204 117 Short-term deposits — 40 Cash and cash equivalents 204 157

Borrowings

Borrowings	12 Months Ended
	Mar. 31, 2022
Disclosure of detailed information about borrowings [abstract]
Borrowings	21. Borrowings We borrow money primarily in the form of bonds and bank loans. These are for a fixed term and may have fixed or floating interest rates or are linked to inflation indices. We use derivatives to manage risks associated with interest rates, inflation rates and foreign exchange. Lease liabilities are also included within borrowings. Our price controls and rate plans lead us to fund our networks within a certain ratio of debt to equity or regulatory asset value and, as a result, we have issued a significant amount of debt. As we continue to invest in our networks, the value of debt is expected to increase over time. To maintain a strong balance sheet and to allow us to access capital markets at commercially acceptable interest rates, we balance the amount of debt we issue with the value of our assets, and we take account of certain other metrics used by credit rating agencies. All borrowings are measured at amortised cost, with the exception of one current liability which was measured at fair value through profit and loss in order to eliminate a measurement mismatch. This current liability has now matured. Borrowings, which include interest-bearing, zero-coupon and inflation-linked debt, overdrafts and collateral payable, are initially recorded at fair value. This normally reflects the proceeds received (net of direct issue costs for liabilities measured at amortised cost). Subsequently, borrowings are stated either: i) at amortised cost; or ii) at fair value though profit and loss. Where a borrowing is held at amortised cost, any difference between the proceeds after direct issue costs and the redemption value is recognised over the term of the borrowing in the income statement using the effective interest method. For the liability held at fair value through profit and loss, interest is calculated using the effective interest method. Where a borrowing or liability is held at fair value, changes in the fair value of the borrowing due to changes in the issuer’s credit risk are recorded in the own credit reserve within equity (see note 28). All other changes in the fair value of the liability are recognised in the income statement within remeasurements (see notes 5 and 6). 2022 2021 £m £m Current Bank loans¹ 8,976 1,022 Bonds² 1,735 1,987 Commercial paper 1,303 628 Lease liabilities 107 99 Other loans — 1 12,121 3,737 Non-current Bank loans 2,211 2,532 Bonds 30,682 24,209 Lease liabilities 451 586 Other loans — 156 33,344 27,483 Total borrowings 45,465 31,220 1. Current bank loans include £8,179 million of borrowings under the bridge facility relating to the acquisition of WPD (31 March 2021: undrawn). The bridge facility allows for the extension of the maturity date up to September 2023 but includes a requirement that the proceeds of the planned sales of NECO and the UK Gas Transmission business are applied to repay the facility. As these are expected to completed within one year the position has been classified as current. 2. Includes a liability held at fair value through profit and loss of £nil (2021: £682 million). 21. Borrowings continued Total borrowings are repayable as follows: 2022 2021 £m £m Less than 1 year 12,121 3,737 In 1 to 2 years 1,410 1,745 In 2 to 3 years 2,544 889 In 3 to 4 years 2,580 2,206 In 4 to 5 years 2,493 1,833 More than 5 years: By instalments 869 927 Other than by instalments 23,448 19,883 45,465 31,220 The fair value of borrowings at 31 March 2022 was £45,624 million (2021: £34,676 million). Where market values were available, the fair value of borrowings (Level 1) was £24,454 million (2021: £20,333 million). Where market values were not available, the fair value of borrowings (Level 2) was £21,170 million (2021: £14,343 million), and calculated by discounting cash flows at prevailing interest rates. The notional amount outstanding of the debt portfolio at 31 March 2022 was £44,055 million (2021: £31,010 million). There have been no new issuances since the year end. Collateral is placed with or received from any derivative counterparty where we have entered into a credit support annex to the ISDA Master Agreement once the current mark-to-market valuation of the trades between the parties exceeds an agreed threshold. Included in current bank loans is £60 million (2021: £582 million) in respect of cash received under collateral agreements. For further details of our borrowing facilities, refer to note 33. For further details of our bonds in issue, please refer to the debt investor section of our website. Unless included herein, the information on our website is unaudited. Certain borrowings, primarily some of our USD denominated bank loans and company car lease contracts, have payments that are linked to LIBOR. LIBOR is being replaced as an interest rate benchmark by alternative reference rates and therefore we are transitioning LIBOR cash flows on our affected contracts in line with the relevant jurisdictions. The migration project is underway, with all affected contracts where we previously paid or received GBP LIBOR amended in the year to 31 March 2022. £314 million (2021: £328 million) of bank loans affected by GBP LIBOR have been transitioned to alternative reference rates. £181 million (2021: £173 million) of lease liabilities affected by USD LIBOR have been transitioned to alternative rates and £110 million (2021: £59 million) of bank loans affected by USD LIBOR have yet to be amended. Financial liability at fair value through profit and loss The financial liability was designated at fair value through profit and loss. Up until the date of maturity in November 2021, the liability was analysed as follows: i. the fair value of the liability at maturity in November 2021 was £699 million (2021: £682 million), which included cumulative changes in fair value attributable to changes in credit risk recognised in other comprehensive income, post tax of £nil (2021: £1 million); ii. the amount repayable at maturity in November 2021 was £699 million (2021: £684 million); and iii. the difference between carrying amount and contractual amount at maturity was £nil (2021: £2 million). This liability was reclassified in order to eliminate a measurement mismatch with derivatives which provide an economic hedge. The associated derivatives were collateralised and did not contain significant exposure to our own credit risk. The presentation of credit risk in other comprehensive income did not, therefore, create or enlarge an accounting mismatch in profit or loss. The change in the fair value attributable to a change in credit risk was calculated as the difference between the total change in the fair value of the liability and the change in the value of the liability due to changes in market risk factors alone. The change in the fair value due to market risk factors was calculated using benchmark yield curves as at the end of the reporting period holding the credit risk margin constant. The fair value of the liability was calculated using observed market prices. 21. Borrowings continued Lease liabilities Lease liabilities are initially measured at the present value of the lease payments expected over the lease term. The discount rate applied is the rate implicit in the lease or if that is not available, then the incremental rate of borrowing for a similar term and similar security. The lease term takes account of exercising any extension options that are at our option if we are reasonably certain to exercise the option and any lease termination options unless we are reasonably certain not to exercise the option. Each lease payment is allocated between the liability and finance cost. The finance cost is charged to the income statement over the lease period using the effective interest rate method. 2022 2021 £m £m Gross lease liabilities are repayable as follows: Less than 1 year 132 114 1 to 5 years 282 321 More than 5 years 259 464 673 899 Less: finance charges allocated to future periods (115) (214) 558 685 The present value of lease liabilities are as follows: Less than 1 year 107 99 1 to 5 years 247 267 More than 5 years 204 319 558 685

Trade and other payables

Trade and other payables	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Trade and other payables	22. Trade and other payables Trade and other payables include amounts owed to suppliers, tax authorities and other parties which are due to be settled within 12 months. The total also includes deferred amounts, some of which represent monies received from customers but for which we have not yet delivered the associated service. These amounts are recognised as revenue when the service is provided. Trade and other payables are initially recognised at fair value and subsequently measured at amortised cost, with the exception of contingent consideration, which is subsequently measured at fair value. 2022 2021 £m £m Trade payables 3,113 2,165 Deferred payables 487 154 Customer contributions¹ 137 138 Social security and other taxes 278 140 Contingent consideration 34 39 Other payables 866 881 4,915 3,517 1. Relates to amounts received from government-related entities for connecting to our networks, where we have obligations remaining under the contract.

Contract liabilities

Contract liabilities	12 Months Ended
	Mar. 31, 2022
Contract liabilities [abstract]
Contract liabilities	23. Contract liabilities Contract liabilities primarily relate to the advance consideration received from customers for construction contracts, mainly in relation to connections, for which revenue is recognised over the life of the asset. 2022 2021 £m £m Current 130 66 Non-current 1,342 1,094 1,472 1,160 Significant changes in the contract liabilities balances during the period are as follows: 2022 2021 £m £m As at 1 April 1,160 1,158 Exchange adjustments 29 (65) Revenue recognised that was included in the contract liability balance at the beginning of the period (53) (96) Increases due to cash received, excluding amounts recognised as revenue during the period 510 262 Reclassification to held for sale (note 10) (174) (99) At 31 March 1,472 1,160

Other non-current liabilities

Other non-current liabilities	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Other non-current liabilities	24. Other non-current liabilities Other non-current liabilities include deferred income and customer contributions which will not be recognised as income until after 31 March 2023. It also includes contingent consideration and other payables that are not due until after that date. Other non-current liabilities are initially recognised at fair value and subsequently measured at amortised cost, with the exception of contingent consideration, which is subsequently measured at fair value. 2022 2021 £m £m Deferred income¹ 41 78 Customer contributions² 421 400 Contingent consideration 7 18 Other payables 336 347 805 843 1. In the year ended 31 March 2021, principally the deferral of profits relating to the sale of property to St William Homes LLP, which were expected to be recognised in future years. In the year ended 31 March 2022, the Group disposed of its interests in St William Homes LLP, resulting in a release of previously deferred profits (see note 16). 2. Relates to amounts received from government-related entities for connecting to our networks, where we have obligations remaining under the contract. There is no material difference between the fair value and the carrying value of other payables.

Pensions and other post-retirem

Pensions and other post-retirement benefits	12 Months Ended
	Mar. 31, 2022
Employee Benefits [Abstract]
Pensions and other post-retirement benefits	25. Pensions and other post-retirement benefits All of our employees are eligible to participate in a pension plan. We have defined contribution (DC) and defined benefit (DB) pension plans in the UK and the US. In the US we also provide healthcare and life insurance benefits to eligible employees, post-retirement. The fair value of associated plan assets and present value of DB obligations are updated annually in accordance with IAS 19 ‘Employee Benefits’. We separately present our UK and US pension plans to show the geographical split. Below we provide a more detailed analysis of the amounts recorded in the primary financial statements and the actuarial assumptions used to value the DB obligations. UK pension plans Defined contribution plan Employees of National Grid’s legacy UK businesses are eligible to join the National Grid UK Retirement Plan (NGUKRP), a section of a Master Trust arrangement managed by Legal & General. National Grid pays contributions into the NGUKRP to provide DC benefits on behalf of its employees, generally providing a double match of member contributions up to a maximum Company contribution of 12% of salary. Additionally, WPD operates a DC pension plan (WPPS) which includes three separate DC sections. Two of the DC sections are closed with no active members at 31 March 2022. There is also an open section, available to all new WPD employees. These plans are defined contribution in nature and are designed to provide members with a pension pot for their retirement. As such, investment risks are borne by the member and there is no legal or constructive obligation on National Grid to pay additional contributions in the instance that investment performance is poor. Payments to these DC plans are charged as an expense as they fall due. Defined benefit plans National Grid operates various DB pension plans in the UK. These include two legally separate sections of the National Grid UK Pension Scheme (Section A and Section B of NGUKPS), three sections of the industry-wide Electricity Supply Pension Scheme (ESPS) and a legacy scheme (WPUPS). During the year, following National Grid’s announcement of its intention to sell its Gas Transmission and Metering businesses, Section B of NGUKPS was reallocated as held for sale. Each of these plans holds its assets in separate Trustee administered funds. The arrangements are managed by Trustee companies with boards consisting of company- and member-appointed directors. These plans are all closed to new members except for the ESPS schemes in very rare circumstances. The arrangements are subject to independent actuarial funding valuations every three years, and following consultation and agreement with the Company, the qualified actuary certifies the employers’ contributions, which, together with the specified contributions payable by the employees and proceeds from the plans’ assets, are expected to be sufficient to fund the benefits payable. The latest full actuarial valuations for each of the DB plans were carried out at 31 March 2019, with the Company agreeing to fund the assessed funding shortfalls for the UK DB plans that were in deficit via recovery plan payments scheduled to finish in November 2024 or earlier, with payments of approximately £130 million across all plans still due to be paid. Separately, National Grid continues to fund the cost of future benefit accrual (over and above member contributions) for each of the DB schemes. In the year to March 2022, the aggregate level of ongoing contributions (excluding recovery plan payments) was £83 million (2021: £50 million; 2020: £70 million). National Grid also pays contributions in respect of the costs of plan administration and the Pension Protection Fund (PPF) levies for most of its DB plans. In addition, for some plans the Company has also agreed to establish security arrangements with charges in favour of the Trustee. The value of security provided across National Grid’s DB plans was £286 million at 31 March 2022, all of which is currently provided in the form of surety bonds but may also be provided as letters of credit or cash. The assets held as security will be paid to the respective section or plan in the event that the relevant supporting employer is subject to an insolvency event or fails to make the required contributions; and applicable to NGEG of ESPS only, if NGET loses its licence to operate under relevant legislation. Counter indemnities have also been taken out to ensure the obligations will be fulfilled. In addition, further cash payments of up to a maximum of £675 million could also become due if certain trigger events occur which have been individually agreed between the plans and their relevant supporting employers. A guarantee has also been provided to Section A of NGUKPS, with the payment contingent on insolvency or on failure to pay pension obligations to Section A and can be claimed against National Grid plc, National Grid Holdings One plc or Lattice Group Limited. US pension plans The US pension plans are governed by a fiduciary committee called the Retirement Plan Committee (RPC). The RPC is structured in accordance with US laws governing retirement plans under the Employee Retirement Income Security Act and comprises appointed employees of the Company. Defined contribution plans National Grid has a DC pension plan which allows employee as well as Company contributions. Non-union employees hired after 1 January 2011, as well as most new hire represented union employees, receive a core contribution into the DC plan ranging from 3% to 9% of salary, irrespective of the employee’s contribution into the plan. Most employees also receive a matching contribution that varies between 25% and 50% of employee contributions up to a maximum of 8% to 10%. The assets of the plans are held in trusts and administered by the RPC. Defined benefit plans National Grid sponsors four non-contributory qualified DB pension plans, which provide vested union employees, and vested non-union employees hired before 1 January 2011, with retirement benefits within prescribed limits as defined by the US Internal Revenue Service. National Grid also provides non-qualified DB pension arrangements for a section of current and former employees, which are closed to new entrants. Benefits under the DB plans generally reflect age, years of service and compensation, and are paid in the form of an annuity or lump sum. An independent actuary performs valuations annually. The Company funds the DB plans by contributing no less than the minimum amount required, but no more than the maximum tax-deductible amount allowed under US Internal Revenue Service regulations. The range of contributions determined under these regulations can vary significantly depending upon the funded status of the plans. At present, there is some flexibility in the amount that is contributed on an annual basis. In general, the Company’s policy for funding the US pension plans is to contribute the amounts collected in rates and capitalised in the rate base during the year, to the extent that the funding is no less than the minimum amount required. For the current financial year, these contributions amounted to approximately £116 million (2021: £110 million). 25. Pensions and other post-retirement benefits continued US other post-retirement benefits National Grid provides healthcare and life insurance benefits to eligible employees, post-retirement. Eligibility is based on certain age and length of service requirements and, in most cases, retirees contribute to the cost of their healthcare coverage. In the US, there is no governmental requirement to pre-fund post-retirement healthcare and life insurance plans. However, in general, the Company’s policy for funding the US retiree healthcare and life insurance plans is to contribute amounts collected in rates and capitalised in the rate base during the year. For the current financial year, these contributions amounted to £17 million (2021: £26 million). For the last few years it has been the Company’s policy to primarily direct contributions to the DB pension plans due to concerns over tax deductible limitations relating to the retiree and healthcare and life insurance plans. Actuarial assumptions On retirement, members of DB plans receive benefits whose value is dependent on factors such as salary and length of pensionable service. National Grid’s obligation in respect of DB pension plans is calculated separately for each DB plan by projecting the estimated amount of future benefit payments that employees have earned for their pensionable service in the current and prior periods. These future benefit payments are discounted to determine the present value of the liabilities. Current service cost and any unrecognised past service cost are recognised immediately. Advice is taken from independent actuaries relating to the appropriateness of the key assumptions applied, including life expectancy, expected salary and pension increases, and inflation. Comparatively small changes in the assumptions used may have a significant effect on the amounts recognised in the consolidated income statement, the consolidated statement of other comprehensive income and the net liability recognised in the consolidated statement of financial position. Remeasurements of pension assets and post-retirement benefit obligations are recognised in full in the period in which they occur in the consolidated statement of other comprehensive income. The Company has applied the following financial assumptions in assessing DB liabilities: UK pensions US pensions US other post-retirement benefits 2022 2021 2020 2022 2021 2020 2022 2021 2020 % % % % % % % % % Discount rate – past service 2.78 2.00 2.35 3.65 3.25 3.30 3.65 3.25 3.30 Discount rate – future service 2.85 2.15 2.35 3.65 3.25 3.30 3.65 3.25 3.30 Rate of increase in RPI – past service 3.60 3.15 2.65 n/a n/a n/a n/a n/a n/a Rate of increase in RPI – future service 3.33 3.00 2.45 n/a n/a n/a n/a n/a n/a Salary increases 3.47 3.40 2.90 4.60 4.30 3.50 4.60 4.30 3.50 Initial healthcare cost trend rate n/a n/a n/a n/a n/a n/a 6.80 7.10 7.00 Ultimate healthcare cost trend rate n/a n/a n/a n/a n/a n/a 4.50 4.50 4.50 For UK pensions, single equivalent financial assumptions are shown above for presentational purposes, although full yield curves have been used in our calculations. The discount rate is determined by reference to high-quality UK corporate bonds at the reporting date. The rate of increase in salaries has been set using a promotional scale where appropriate. The rates of increases stated are not indicative of historical increases awarded or a guarantee of future increase, but merely an appropriate assumption used in assessing DB liabilities. Retail Price Index (RPI) is the key assumption that determines assumed increases in pensions in payment and deferment in the UK only. Discount rates for US pension liabilities have been determined by reference to appropriate yields on high-quality US corporate bonds at the reporting date based on the duration of plan liabilities. The healthcare cost trend rate is expected to reach the ultimate trend rate by 2031 (2021: 2030). The table below sets out the projected life expectancies adopted for the UK and US pension arrangements: UK pensions US pensions 2022 2021 2020 2022 2021 2020 years years years years years years Assumed life expectations for a retiree age 65 Males 22.0 21.8 22.1 21.4 21.6 20.9 Females 23.8 23.7 23.8 23.6 24.0 23.4 In 20 years: Males 23.2 23.1 23.3 23.1 23.2 22.5 Females 25.2 25.2 25.3 25.3 25.5 25.1 The weighted average duration of the DB obligation for each category of plan is 14 years for UK pension plans; 13 years for US pension plans and UK pensions US pensions US other 2022 2021 2022 2021 2022 2021 % % % % % % Active members 16 8 36 35 34 34 Deferred members 10 14 9 9 — — Pensioner members 74 78 55 56 66 66 For sensitivity analysis see note 35. 25. Pensions and other post-retirement benefits continued Amounts recognised in the consolidated statement of financial position 2022 2021 £m £m Present value of funded obligations (23,541) (23,283) Fair value of plan assets 27,013 24,388 3,472 1,105 Present value of unfunded obligations (326) (324) Other post-employment liabilities (71) (66) Net defined benefit asset/(liability) 3,075 715 Represented by: Liabilities (810) (1,032) Assets 3,885 1,747 3,075 715 The geographical split of pensions and other post-retirement benefits is as shown below: UK pensions US pensions US other Total 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Present value of funded obligations (14,197) (13,571) (6,531) (6,681) (2,813) (3,031) (23,541) (23,283) Fair value of plan assets 16,865 14,680 7,263 6,909 2,885 2,799 27,013 24,388 2,668 1,109 732 228 72 (232) 3,472 1,105 Present value of unfunded obligations (78) (74) (248) (250) — — (326) (324) Other post-employment liabilities — — — — (71) (66) (71) (66) Net defined benefit asset/(liability) 2,590 1,035 484 (22) 1 (298) 3,075 715 Represented by: Liabilities (78) (74) (248) (393) (484) (565) (810) (1,032) Assets 2,668 1,109 732 371 485 267 3,885 1,747 2,590 1,035 484 (22) 1 (298) 3,075 715 The recognition of the pension assets in the UK and in the US reflects legal and actuarial advice that we have taken regarding recognition of surpluses under IFRIC 14. In the UK, the Group has an unconditional right to a refund in the event of a winding up. In the US, surplus assets of a Plan may be used to pay for future benefits expected to be earned under that Plan. 25. Pensions and other post-retirement benefits continued Amounts recognised in the income statement and statement of other comprehensive income The expense or income arising from all Group retirement benefit arrangements recognised in the Group income statements is shown below: 2022 2021 2020 £m £m £m Included within operating costs Administration costs 20 18 16 Included within payroll costs Defined benefit plan costs: Current service cost 223 175 178 Past service cost – augmentations 1 — — Past service cost/(credit) – redundancies 1 (1) — Special termination benefit cost – redundancies 9 5 2 234 179 180 Included within finance income and costs Net interest (income)/cost (2) 38 23 Total included in income statement¹ 252 235 219 Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations 2 2,481 1,408 (724) Exchange adjustments 7 186 (97) Total included in the statement of other comprehensive income³ 2,488 1,594 (821) 1. Amounts shown in the table above include operating costs of £4 million (2021: £3 million; 2020: £4 million); payroll costs of £10 million (2021: £10 million; 2020: £10 million); and net interest income of £2 million (2021: £13 million; 2020: £11 million) presented within profit from discontinued operations. These amounts all relate to UK pensions. 2. For the year ended 31 March 2021, this included actuarial losses from the purchase of buy-in policies of £0.1 billion. 3. Amounts shown in the table above include remeasurements of pension assets and post-retirement benefit obligations resulting in a gain of £309 million (2021: £250 million loss; 2020: £58 million gain) presented within discontinued operations. These amounts all relate to UK pensions. The geographical split of pensions and other post-retirement benefits is shown below: UK pensions US pensions US other post-retirement benefits 2022 2021 2020 2022 2021 2020 2022 2021 2020 £m £m £m £m £m £m £m £m £m Included within operating costs Administration costs 11 9 9 7 7 6 2 2 1 Included within payroll costs Defined benefit plan costs: Current service cost 83 28 33 101 104 100 39 43 45 Past service cost – augmentations 1 — — — — — — — — Past service cost/(credit) – redundancies 1 (1) — — — — — — — Special termination benefit cost – redundancies 9 5 2 — — — — — — 94 32 35 101 104 100 39 43 45 Included within finance income and costs Net interest (income)/cost (7) (38) (31) — 35 21 5 41 33 Total included in income statement 98 3 13 108 146 127 46 86 79 Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations 1 1,577 (622) 143 532 1,017 (588) 372 1,013 (279) Exchange adjustments — — — 11 83 (42) (4) 103 (55) Total included in the statement of other comprehensive income 1,577 (622) 143 543 1,100 (630) 368 1,116 (334) 1. For the year ended 31 March 2021, UK pensions is stated after actuarial losses from the purchase of buy-in policies of £0.1 billion. 25. Pensions and other post-retirement benefits continued Reconciliation of the net defined benefit asset/(liability) UK pensions US pensions US other Total 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Opening net defined benefit asset/(liability) 1,035 1,520 (22) (1,113) (298) (1,360) 715 (953) Cost recognised in the income statement (including discontinued operations) (98) (3) (108) (146) (46) (86) (252) (235) Remeasurement and foreign exchange effects recognised in the statement of other comprehensive income 1,577 (622) 543 1,100 368 1,116 2,488 1,594 Employer contributions 167 138 116 110 17 26 300 274 Other movements 7 2 — — (29) (16) (22) (14) Acquisition of WPD (note 37) 566 — — — — — 566 — Reclassification to held for sale (note 10) (664) — (45) 27 (11) 22 (720) 49 Closing net defined benefit asset/(liability) 2,590 1,035 484 (22) 1 (298) 3,075 715 Changes in the present value of defined benefit obligations (including unfunded obligations) The table below shows the movement in defined benefit obligations across our DB plans over the year. UK pensions US pensions US other Total 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Opening defined benefit obligations (13,645) (12,844) (6,931) (8,085) (3,031) (3,697) (23,607) (24,626) Current service cost (83) (28) (101) (104) (39) (43) (223) (175) Interest cost (88) (296) (240) (243) (100) (112) (428) (651) Actuarial (losses)/gains – experience (627) (21) (24) (72) 107 216 (544) 123 Actuarial gains/(losses) – demographic assumptions 133 (1) 100 — 71 — 304 (1) Actuarial gains/(losses) – financial assumptions 1,387 (1,181) 329 (62) 192 (25) 1,908 (1,268) Past service (cost)/credit – redundancies (1) 1 — — — — (1) 1 Special termination benefit cost – redundancies (9) (5) — — — — (9) (5) Past service cost – augmentations (1) — — — — — (1) — Medicare subsidy received — — — — (24) (25) (24) (25) Employee contributions (8) (1) — — — — (8) (1) Benefits paid 919 731 403 371 159 144 1,481 1,246 Exchange adjustments — — (327) 804 (140) 362 (467) 1,166 Acquisition of WPD (7,096) — — — — — (7,096) — Reclassification to held for sale 4,844 — 12 460 (8) 149 4,848 609 Closing defined benefit obligations (14,275) (13,645) (6,779) (6,931) (2,813) (3,031) (23,867) (23,607) 25. Pensions and other post-retirement benefits continued Changes in the value of plan assets The table below shows the movement in pension assets across our DB plans over the year. UK pensions US pensions US other Total 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Opening fair value of plan assets 14,680 14,364 6,909 6,972 2,799 2,412 24,388 23,748 Interest income 95 334 240 208 95 71 430 613 Return on plan assets in excess of interest 1 684 581 127 1,151 2 822 813 2,554 Administration costs (11) (9) (7) (7) (2) (2) (20) (18) Employer contributions 167 138 116 110 17 26 300 274 Employee contributions 8 1 — — — — 8 1 Benefits paid (912) (729) (403) (371) (159) (144) (1,474) (1,244) Exchange adjustments — — 338 (721) 136 (259) 474 (980) Acquisition of WPD 7,662 — — — — — 7,662 — Reclassification to held for sale (5,508) — (57) (433) (3) (127) (5,568) (560) Closing fair value of plan assets 16,865 14,680 7,263 6,909 2,885 2,799 27,013 24,388 Actual return on plan assets 779 915 367 1,359 97 893 1,243 3,167 Expected contributions to plans 146 93 74 113 14 6 234 212 1. For the year ended 31 March 2021, this included actuarial losses from the purchase of buy-in policies of £0.1 billion. Asset allocations The allocation of assets by asset class is set out below. Within these asset allocations there is significant diversification across regions, asset managers, currencies and bond categories. UK pensions 2022 2021 2020 Quoted Unquoted Total Quoted Unquoted Total Quoted Unquoted Total £m £m £m £m £m £m £m £m £m Equities 1,458 474 1,932 555 801 1,356 732 732 1,464 Corporate bonds 2,741 — 2,741 3,730 37 3,767 3,837 — 3,837 Government securities 786 — 786 1,836 — 1,836 2,051 — 2,051 Property 122 1,002 1,124 104 565 669 103 585 688 Diversified alternatives 1,334 432 1,766 — 712 712 — 893 893 Liability-matching assets 2,023 ¹ 6,090 ² 8,113 ³ 1,731 ¹ 4,133 ² 5,864 ³ 1,704 ¹ 3,278 ² 4,982 ³ Longevity swap — (80) (80) — (64) (64) — (51) (51) Cash and cash equivalents 477 — 477 34 250 284 29 222 251 Other (including net current assets and liabilities) 16 (10) 6 — 256 256 — 249 249 8,957 7,908 16,865 ⁴ 7,990 6,690 14,680 8,456 5,908 14,364 1. Consists of pooled funds which invest mainly in fixed interest securities. 2. Includes buy-in policies held by NGUKPS with a total value of £2.7 billion (2021: £4.1 billion; 2020: £3.3 billion). 3. Included within liability-matching assets above is £6.6 billion (2021: £2.5 billion; 2020: £2.8 billion) of repurchase agreements. These are used to increase the market exposure of the liability-matching portfolios. 4. The fair value of plan assets for NGUKPS Section A includes £32 million (2021: £nil; 2020: £nil) of direct holdings in WPD debt instruments. 25. Pensions and other post-retirement benefits continued US pensions 2022 2021 2020 Quoted Unquoted Total Quoted Unquoted Total Quoted Unquoted Total £m £m £m £m £m £m £m £m £m Equities 272 1,904 2,176 560 2,359 2,919 467 2,043 2,510 Corporate bonds 2,311 697 3,008 1,547 507 2,054 1,640 518 2,158 Government securities 335 715 1,050 354 527 881 535 732 1,267 Property — 295 295 — 264 264 — 307 307 Diversified alternatives 142 364 506 167 458 625 162 464 626 Infrastructure — 182 182 — 130 130 — 121 121 Cash and cash equivalents 31 — 31 24 — 24 24 — 24 Other (including net current assets and liabilities) 12 3 15 12 — 12 (44) 3 (41) 3,103 4,160 7,263 2,664 4,245 6,909 2,784 4,188 6,972 US other post-retirement benefits 2022 2021 2020 Quoted Unquoted Total Quoted Unquoted Total Quoted Unquoted Total £m £m £m £m £m £m £m £m £m Equities 185 1,013 1,198 419 1,303 1,722 353 1,037 1,390 Corporate bonds 723 2 725 13 — 13 15 — 15 Government securities 511 2 513 533 3 536 551 1 552 Diversified alternatives 144 120 264 185 172 357 162 161 323 Other¹ — 185 185 — 171 171 — 132 132 1,563 1,322 2,885 1,150 1,649 2,799 1,081 1,331 2,412 1. Other primarily comprises insurance contracts. Main defined benefit risks National Grid underwrites the financial and demographic risks associated with our DB plans. Although the governing bodies have sole responsibility for setting investment strategies and managing risks, National Grid closely works with and supports the governing bodies of each plan, to assist them in mitigating the risks associated with their plans and to ensure that the plans are funded to meet their obligations. The most significant risks associated with the DB plans are: Main risks Description and mitigation Investment risk The plans invest in a variety of asset classes, with actual returns likely to differ from the underlying discount rate adopted, impacting on the funding position of the plan through the net balance sheet asset or liability. Each plan seeks to balance the level of investment return required with the risk that it can afford to take, to design the most appropriate investment portfolio. Changes in bond yields Liabilities are calculated using discount rates set with reference to the yields in high-quality bonds prevailing in the UK and US debt markets and will fluctuate as yields change. Volatility of the net balance sheet asset or liability is controlled through liability-matching strategies. The investment strategies allow for the use of synthetic as well as physical assets to be used to hedge interest rate risk. Inflation risk Changes in inflation will affect the current and future pensions but are partially mitigated through investing in inflation-matching assets and hedging instruments as well as bulk annuity buy-in policies. The investment strategies allow for the use of synthetic as well as physical assets to be used to hedge inflation risk. Member longevity Longevity is a key driver of liabilities and changes in life expectancy have a direct impact on liabilities. Improvements in life expectancy will lead to pension payments being paid for longer than expected and benefits ultimately being more expensive. This risk has been partly mitigated by recent scheme investment transactions including a longevity insurance contract (longevity swap) for NGEG of ESPS and two buy-in policies for Section A of NGUKPS. Counterparty risk This is managed by having a diverse range of counterparties and through having a strong collateralisation process (including for the longevity swap held by NGEG of ESPS). Measurement and management of counterparty risk is delegated to the relevant investment managers. For our bulk annuity policies, various termination provisions were introduced in the contracts, managing our exposure to counterparty risk. The insurers’ operational performance and financial strength are monitored on a regular basis. Default risk Investments are predominantly made in regulated markets in assets considered to be of investment grade. Where investments are made either in non-investment grade assets or outside of regulated markets, investment levels are kept to prudent levels and subject to agreed control ranges, to control the risk. Liquidity risk The pension plans hold sufficient cash to meet benefit requirements, with other investments being held in liquid or realisable assets to meet unexpected cash flow requirements. The plans do not borrow money, or act as guarantor, to provide liquidity to other parties (unless it is temporary). Currency risk Fluctuations in the value of foreign denominated assets due to exposure to currency exchange rates is managed through a combination of segregated currency hedging overlay and currency hedging carried out by some of the investment managers. 25. Pensions and other post-retirement benefits continued DB plan investment strategies The Trustees and RPC, after taking advice from professional investment advisors and in consultation with National Grid, set their key principles, including expected returns, risk and liquidity requirements. They formulate an investment strategy to manage risk through diversification, taking into account expected contributions, maturity of the pension liabilities, and in the UK, the strength of the covenant. These strategies allocate investments between return-seeking assets such as equities and property, and liability-matching assets such as buy-in policies, government securities and corporate bonds which are intended to protect the funding position. The approximate investment allocations for our plans at 31 March 2022 are as follows: UK pensions US pensions US other post-retirement benefits % % % Return-seeking assets 28 41 51 Liability-matching assets 72 59 49 The governing bodies can generally delegate responsibility for the selection of specific bonds, securities and other investments to appointed investment managers. Investment managers are selected based on the required skills, expertise in those markets, process and financial security to manage the investments. Their performance is regularly reviewed against measurable objectives, consistent with each pension plan’s long-term objectives and accepted risk levels. In the UK, each of our pension plans has Responsible Investment (RI) Policies, which take into account Environmental, Social and Governance (ESG) factors and generally incorporate the six UN-backed Principles for Responsible Investment (UNPRI). Each of the Trustee boards believes that ESG factors can be material to financial outcomes and should therefore be considered alongside other factors. They recognise that their primary responsibility remains a fiduciary one, i.e., their first duty is to ensure the best possible return on investments with the appropriate level of risk. However, they also recognise the increasing materiality of ESG factors and that they have a fiduciary and regulatory duty to consider RI, including ESG factors and their potential impact on the quality and sustainability of long-term investment returns. The principle defined contribution arrangement in the UK, the NGUKRP, is operated by Legal & General, which embeds ESG factors in the investment options offered to members. As well as offering a range of self-select ethical funds, it directly incorporates its Climate Impact Pledge into the default investment option, which acts to align the fund to a carbon net zero future. Whilst in the US there is no regulatory requirement to have ESG-specific principles embedded in investment policies, our investment managers often utilise ESG principles to inform their decision-making process.

Provisions

Provisions	12 Months Ended
	Mar. 31, 2022
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
Provisions	26. Provisions Provisions are recognised when an obligation exists resulting from a past event, and it is probable that cash will be paid to settle it, but the exact amount of cash required can only be estimated. The majority of our provisions relate to environmental remediation, specifically in relation to certain Superfund sites in the US, being sites we own or have owned in the past where hazardous substances are present as a result of the historic operations of manufactured gas plants in Brooklyn, New York. We also recognise provisions for decommissioning costs for various assets we would be required to remove at the end of their lives; the costs associated with restructuring plans; the costs in respect of insured past events; for certain Ofgem arrangements in respect of specific interconnectors which require the return of excess revenues above a cap; and for lease contracts we have entered into that are now loss-making. In determining the quantum of the provision we recognise, we make estimates in relation to management’s best judgement of the evaluation of the likelihood and the probability of exposure to potential loss, and the costs that would be incurred. Should circumstances change following unforeseeable developments, the likelihood or quantum could alter. Provisions are recognised where a legal or constructive obligation exists at the reporting date, as a result of a past event, where the amount of the obligation can be reliably estimated and where the outflow of economic benefit is probable. The quantum of the provision recognised for decommissioning, environmental, restructuring and other costs is based on estimated future expenditure, discounted to present values. An initial estimate of decommissioning and environmental costs attributable to property, plant and equipment is recorded as part of the original cost of the related property, plant and equipment. Provisions to decommission significant portions of our regulated transmission and distribution assets are not recognised where no legal obligations exist, and a realistic alternative exists to incurring costs to decommission assets at the end of their life. In any case, even if a legal or constructive obligation did exist, it is not currently determinable when remediation work would take place and therefore no provision would be recorded at this point. Changes in the provision arising from revised estimates, discount rates or changes in the expected timing of expenditure that relates to property, plant and equipment are recorded as adjustments to their carrying value and depreciated prospectively over their remaining estimated useful economic lives; otherwise such changes are recognised in the income statement. The unwinding of the discount is included within the income statement within finance costs. Environmental £m Decommissioning £m Restructuring £m Other £m Total provisions £m At 1 April 2020 2,071 254 35 294 2,654 Exchange adjustments (185) (9) (1) (21) (216) Additions 26 42 11 67 146 Unused amounts reversed (38) (27) — (16) (81) Unwinding of discount 66 7 — 5 78 Utilised (161) (16) (19) (62) (258) Reclassification to held for sale (note 10) (79) (7) — (10) (96) At 31 March 2021 1,700 244 26 257 2,227 Exchange adjustments 82 4 1 10 97 Additions 158 37 16 212 423 Acquisition of WPD (note 37) — 37 — 29 66 Unused amounts reversed (25) (4) (1) (31) (61) Unwinding of discount 64 6 — 3 73 Utilised (99) (26) (22) (47) (194) Reclassification to held for sale (note 10) (3) (40) (3) (46) (92) At 31 March 2022 1,877 258 17 387 2,539 2022 2021 £m £m Current 240 260 Non-current 2,299 1,967 2,539 2,227 26. Provisions continued Environmental provisions The environmental provision represents the estimated restoration and remediation costs relating to a number of sites owned and managed by subsidiary undertakings, together with certain US sites that National Grid no longer owns. The environmental provision is as follows: 2022 2021 Discounted Real undiscounted Real Discounted Real undiscounted Real discount rate UK sites 152 160 0.5 % 167 171 0.5 % US sites 1,725 1,789 0.5 % 1,533 1,583 0.5 % 1,877 1,949 1,700 1,754 The remediation expenditure in the UK relates to old gas manufacturing sites and also to electricity transmission sites. Cash flows are expected to be incurred until 2069. A number of estimation uncertainties affect the calculation of the provision, including the impact of regulation, the accuracy of site surveys, unexpected contaminants, transportation costs, the impact of alternative technologies, the expected timing and duration of cash flows, and changes in the real discount rate. This provision incorporates our best estimate of the financial effect of these uncertainties, but future changes in any of the assumptions could materially impact the calculation of the provision. The undiscounted amount is the undiscounted best estimate of the liability having regard to these uncertainties. The remediation expenditure in the US is expected to be incurred until 2069, of which the majority relates to three Superfund sites (being sites where hazardous substances are present as a result of the historic operations of manufactured gas plants in Brooklyn, New York). The weighted average duration of the cash flows is 11 years. The uncertainties regarding the calculation of this provision are similar to those considered in respect of UK sites. Under the terms of our rate plans, we are entitled to recovery of environmental clean-up costs from rate payers. Decommissioning provisions The decommissioning provisions include £258 million (2021: £244 million) of expenditure relating to asset retirement obligations estimated to be incurred until 2104. Restructuring provisions In 2022, we continued to undertake design and implementation activities in respect of our new operating model and cost efficiency programme, which resulted in the recognition of an increased provision of £16 million in the year (2021: £11 million). The income statement expense relating to the provision has been treated as an exceptional item, and details are provided in note 5. Other provisions Included within other provisions at 31 March 2022 are the following amounts: • £163 million (2021: £166 million) of estimated liabilities in respect of past events insured by insurance subsidiary undertakings, including employer liability claims. In accordance with insurance industry practice, these estimates are based on experience from previous years, but we currently expect that cash flows will be incurred until 2037; • £121 million (2021: £nil) of estimated liabilities in respect of interconnector excess revenues which will be repayable in future reporting periods in accordance with the cap and floor regime constructed by Ofgem (see notes 3 and 38). These estimates are based on the respective interconnectors’ performance against their cumulative caps and cash outflows will be required to settle these liabilities by the financial year ending 31 March 2028; • £28 million (2021: £27 million) in respect of onerous lease commitments and rates payable on surplus properties with expenditure expected to be incurred until 2039; and • £26 million (2021: £13 million) in respect of emissions provisions with expenditure expected to be incurred until 2023.

Share capital

Share capital	12 Months Ended
	Mar. 31, 2022
Share Capital, Reserves And Other Equity Interest [Abstract]
Share capital	27. Share capital Ordinary share capital represents the total number of shares issued which are publicly traded. We also disclose the number of treasury shares the Company holds, which are shares that the Company has bought itself, predominantly to actively manage scrip issuances and settle employee share option and reward plan liabilities. Share capital is accounted for as an equity instrument. An equity instrument is any contract that includes a residual interest in the consolidated assets of the Company after deducting all its liabilities and is recorded at the proceeds received, net of direct issue costs, with an amount equal to the nominal amount of the shares issued included in the share capital account and the balance recorded in the share premium account. Allotted, called-up and fully paid million £m At 1 April 2020 3,780 470 Issued during the year in lieu of dividends¹ 35 4 At 31 March 2021 3,815 474 Issued during the year in lieu of dividends¹ 89 11 At 31 March 2022 3,904 485 1. The issue of shares under the scrip dividend programme is considered to be a bonus issue under the terms of the Companies Act 2006, and the nominal value of the shares is charged to the share premium account. The share capital of the Company consists of ordinary shares of 12 204 ⁄ 473 pence nominal value each including ADSs. The ordinary shares and ADSs allow holders to receive dividends and vote at general meetings of the Company. The Company holds treasury shares but may not exercise any rights over these shares including the entitlement to vote or receive dividends. There are no restrictions on the transfer or sale of ordinary shares. In line with the provisions of the Companies Act 2006, the Company has amended its Articles of Association and ceased to have authorised share capital. The Company has implemented a share forfeiture programme following the completion of a tracing and notification exercise to any shareholders who have not had contact with the Company over the past 12 years, in accordance with the provisions set out in the Company’s Articles of Association. Under the share forfeiture programme, the shares and dividends associated with shares of untraced members have been forfeited, with the resulting proceeds transferred to the Company to use in line with the Company’s corporate responsibility strategy. During the financial year, the Company received £16 million of proceeds from the sale of untraced shares and derecognised £32 million of liabilities related to unclaimed dividends, which are reflected in share premium and the income statement respectively. Treasury shares At 31 March 2022, the Company held 259 million (2021: 266 million) of its own shares. The market value of these shares as at 31 March 2022 was £3,038 million (2021: £2,296 million). For the benefit of employees and in connection with the operation of the Company’s various share plans, the Company made the following transactions in respect of its own shares during the year ended 31 March 2022: i. During the year, 4 million (2021: 4 million) treasury shares were gifted to National Grid Employee Share Trusts and 2 million (2021: 2 million) treasury shares were re-issued in relation to employee share schemes, in total representing 0.2% (2021: 0.2%) of the ordinary shares in issue as at 31 March 2022. The nominal value of these shares was £1 million (2021: £1 million) and the total proceeds received were £17 million (2021: £17 million). National Grid settles share awards under its Long Term Incentive Plan and the Save As You Earn scheme, by the transfer of treasury shares to its employee share trusts. ii. During the year, the Company made payments totalling £3 million (2021: £2 million) to National Grid Employee Share Trusts to enable the Trustees to make purchases of National Grid plc shares to settle share awards in relation to all employee share plans and discretionary reward plans. The cost of such purchases is deducted from retained earnings in the period that the transaction occurs. The maximum number of ordinary shares held in treasury during the year was 266 million (2021: 272 million) representing 6.8% (2021: 7.1%) of the ordinary shares in issue as at 31 March 2022 and having a nominal value of £33 million (2021: £34 million).

Other equity reserves

Other equity reserves	12 Months Ended
	Mar. 31, 2022
Disclosure of reserves within equity [abstract]
Other equity reserves	28. Other equity reserves Other equity reserves are different categories of equity as required by accounting standards and represent the impact of a number of our historical transactions or fair value movements on certain financial instruments that the Company holds. Other equity reserves comprise the translation reserve (see accounting policy C in note 1), cash flow hedge reserve and the cost of hedging reserve (see note 32), debt instruments at fair value through other comprehensive income reserve (FVOCI debt) and equity investments at fair value through other comprehensive income reserve (FVOCI equity) (see note 15), the capital redemption reserve and the merger reserve. The merger reserve arose as a result of the application of merger accounting principles under the then prevailing UK GAAP, which under IFRS 1 was retained for mergers that occurred prior to the IFRS transition date. Under merger accounting principles, the difference between the carrying amount of the capital structure of the acquiring vehicle and that of the acquired business was treated as a merger difference and included within reserves. The merger reserve represents the difference between the carrying value of subsidiary undertaking investments and their respective capital structures following the Lattice demerger from BG Group plc and the 1999 Lattice refinancing. The cash flow hedge reserve will amortise as the committed future cash flows from borrowings are paid or capitalised in fixed assets (as described in note 32). Cost of hedging, FVOCI debt and FVOCI equity reserves arose as a result of the adoption of IFRS 9 on 1 April 2018. See note 15 for further detail on FVOCI debt and FVOCI equity reserves; and note 32 in respect of cost of hedging reserve. As the amounts included in other equity reserves are not attributable to any of the other classes of equity presented, they have been disclosed as a separate classification of equity. Translation £m Cash flow hedge £m Cost of hedging £m FVOCI equity £m FVOCI Own Capital redemption £m Merger £m Total £m At 1 April 2019 750 61 17 34 48 13 19 (5,165) (4,223) Exchange adjustments¹ 560 — — — — — — — 560 Net losses taken to equity — (142) (33) (13) (15) (3) — — (206) Share of net losses of associates taken to equity — (5) — — — — — — (5) Transferred to profit or loss — 14 (45) — — — — — (31) Net losses in respect of cash flow hedging of capital expenditure — (17) — — — — — — (17) Tax — 29 11 4 (2) — — — 42 Cash flow hedges transferred to the statement of financial position, net of tax — (15) — — — — — — (15) At 1 April 2020 1,310 (75) (50) 25 31 10 19 (5,165) (3,895) Exchange adjustments¹ (1,345) — — — — — — — (1,345) Net gains/(losses) taken to equity — 14 11 36 80 (11) — — 130 Share of net gains of associates taken to equity — 1 — — — — — — 1 Transferred to profit or loss — 56 3 — — — — — 59 Net losses in respect of cash flow hedging of capital expenditure — (14) — — — — — — (14) Tax — (13) 8 (10) — 2 — — (13) Cash flow hedges transferred to the statement of financial position, net of tax — (17) — — — — — — (17) At 1 April 2021 (35) (48) (28) 51 111 1 19 (5,165) (5,094) Exchange adjustments¹ 629 — — — — — — — 629 Net losses taken to equity² — (96) (2) (70) (11) (1) — — (180) Share of net gains of associates taken to equity — 1 — — — — — — 1 Transferred to profit or loss — 40 (1) — — — — — 39 Net losses in respect of cash flow hedging of capital expenditure — (1) — — — — — — (1) Tax — 11 2 19 3 — — — 35 Cash flow hedges transferred to the statement of financial position, net of tax — 8 — — — — — — 8 At 31 March 2022 594 (85) (29) — 103 — 19 (5,165) (4,563) 1. The exchange adjustments recorded in the translation reserve comprise a gain of £754 million (2021: loss of £1,507 million; 2020: gain of £545 million) relating to the translation of foreign operations offset by a loss of £125 million (2021: gain of £183 million; 2020: gain of £5 million) relating to borrowings, cross-currency swaps and foreign exchange forward contracts used to hedge the net investment in non-sterling denominated subsidiaries.

Net debt

Net debt	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Net debt	29. Net debt We define net debt as the amount of borrowings and financing derivatives less cash and current financial investments. (a) Composition of net debt Net debt is comprised as follows: 2022 2021 2020 £m £m £m Cash and cash equivalents (see note 20) 204 157 73 Current financial investments (see note 15) 3,145 2,342 1,998 Borrowings (see note 21) (45,465) (31,220) (30,794) Financing derivatives¹ (see note 17) (693) 175 133 (42,809) (28,546) (28,590) 1. The financing derivatives balance included in net debt excludes the commodity derivatives (see note 17). (b) Analysis of changes in net debt Notes Cash and cash equivalents £m Financial investments 1 £m Borrowings £m Financing derivatives £m Total 2 £m At 1 April 2019 252 1,981 (28,730) (32) (26,529) Impact of transition to IFRS 16 — — (474) — (474) Cash flow (183) (42) 450 450 675 Fair value gains and losses — 1 (57) (246) (302) Foreign exchange movements 4 24 (807) — (779) Interest income/(charges) 6 — 34 (1,092) (39) (1,097) Other non-cash movements — — (84) — (84) At 1 April 2020 73 1,998 (30,794) 133 (28,590) Cash flow 95 429 (2,336) 4 (1,808) Fair value gains and losses — 14 159 31 204 Foreign exchange movements (7) (106) 1,710 — 1,597 Interest income/(charges) 6 — 7 (946) 7 (932) Other non-cash movements — — (136) — (136) Reclassification to held for sale 10 (4) — 1,123 — 1,119 At 1 April 2021 157 2,342 (31,220) 175 (28,546) Cash flow 29(c) 9 752 (9,993) 262 (8,970) Fair value gains and losses — (12) 286 (604) (330) Foreign exchange movements 5 53 (652) — (594) Interest income/(charges) 6 — 43 (1,177) (59) (1,193) Other non-cash movements — (15) 34 — 19 Acquisition of WPD 37 44 69 (8,286) 26 (8,147) Reclassification to held for sale³ 10 (11) (87) 5,543 (493) 4,952 At 31 March 2022 204 3,145 (45,465) (693) (42,809) Balances at 31 March 2022 comprise: Non-current assets — — — 264 264 Current assets 204 3,145 — 34 3,383 Current liabilities — — (12,121) (136) (12,257) Non-current liabilities — — (33,344) (855) (34,199) 204 3,145 (45,465) (693) (42,809) 1. Cash flows on current financial investments comprise £29 million (2021: £7 million; 2020: £35 million) of interest received and £781 million of cash outflows (2021: £436 million outflows; 2020: £7 million outflows) of net cash flow movements in short-term financial investments, as presented in the consolidated cash flow statement. 2. Includes accrued interest at 31 March 2022 of £351 million (2021: £263 million; 2020: £246 million). 3. Reclassification to held for sale represents the opening net debt position of the UK Gas Transmission business. The closing net debt position of the UK Gas Transmission business is disclosed in note 10. 29. Net debt continued (c) Reconciliation of cash flow from liabilities within net debt to cash flow statement 2022 2021 1 2020 1 Borrowings and other Financing derivatives Borrowings and other Financing derivatives Borrowings and other Financing derivatives Cash flows per financing activities section of cash flow statement: Proceeds received from loans 12,347 — 5,150 — 3,921 — Repayment of loans (1,261) — (1,654) — (3,037) — Payments of lease liabilities (117) — (107) — (115) — Net movements in short-term borrowings (11) — (619) — (562) — Cash inflows on derivatives — 20 — 17 — 46 Cash outflows on derivatives — (114) — (183) — (245) Interest paid (998) (55) (711) (42) (802) (65) Cash flows per financing activities section of cash flow statement 9,960 (149) 2,059 (208) (595) (264) Adjustments: Non-net debt-related items 33 — 29 — 34 — Derivative cash (outflow)/inflow in relation to capital expenditure — (8) — 10 — 13 Derivative cash inflows per investing section of cash flow statement — 17 — 225 — 58 Derivative cash outflows per investing section of cash flow statement — (122) — (81) — (281) Cash flows relating to financing liabilities within net debt 9,993 (262) 2,088 (54) (561) (474) Analysis of changes in net debt: Borrowings 9,993 — 2,088 — (561) — Financing derivatives — (262) — (54) — (474) Cash flow movements relating to financing liabilities within net debt 9,993 (262) 2,088 (54) (561) (474) 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. (d) Reconciliation of changes in liabilities arising from financing activities The table below reconciles changes in liabilities arising from financing activities, including both changes arising from cash flows and non-cash changes. For the purposes of this table, the liabilities arising from financing activities are those for which cash flows were, or future cash flows will be, classified in the consolidated cash flow statement within financing activities. As a result we have separately disclosed the reconciliation below, excluding derivatives associated with our net investment hedges and derivatives associated with the hedging of capital expenditure, given that they are both classified in the consolidated cash flow statement within investing activities. Notes Borrowings £m Financing derivatives £m Total £m At 1 April 2019 (28,730) 228 (28,502) Impact of transition to IFRS 16 (474) — (474) Cash flow¹ 450 240 690 Fair value gains and losses (57) (231) (288) Foreign exchange movements (807) — (807) Interest charges 6 (1,092) (9) (1,101) Other non-cash movements (84) — (84) At 1 April 2020 (30,794) 228 (30,566) Cash flow¹ (2,336) 158 (2,178) Fair value gains and losses 159 (301) (142) Foreign exchange movements 1,710 — 1,710 Interest charges 6 (946) 11 (935) Other non-cash movements (136) — (136) Reclassification to held for sale 10 1,123 — 1,123 At 1 April 2021 (31,220) 96 (31,124) Cash flow (9,993) 149 (9,844) Fair value gains and losses 286 (472) (186) Foreign exchange movements (652) — (652) Interest charges 6 (1,177) (54) (1,231) Other non-cash movements 34 — 34 Acquisition of WPD 37 (8,286) 26 (8,260) Reclassification to held for sale² 10 5,543 (495) 5,048 At 31 March 2022 (45,465) (750) (46,215) 1. Comparative amounts include financing cash flows attributable to the UK Gas Transmission business which was classified as a discontinued operation in the year (see notes 1 and 10). In order to reconcile financing cash flows to the consolidated cash flow statement for the years ended 31 March 2021 and 2020, cash flows from financing activities for both continuing operations and discontinued operations should be included, along with non-debt related items in note 29(c).

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Mar. 31, 2022
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
Commitments and contingencies	30. Commitments and contingencies Commitments are those amounts that we are contractually required to pay in the future as long as the other party meets its obligations. These commitments primarily relate to energy purchase agreements and contracts for the purchase of assets which, in many cases, extend over a long period of time. We also disclose any contingencies, which include guarantees that companies have given, where we pledge assets against current obligations that will remain for a specific period. Contingent assets are disclosed where the Group concludes that an inflow of economic benefits is probable. 2022 2021 £m £m Future capital expenditure Contracted for but not provided 1 2,881 2,716 Energy purchase commitments 2 Less than 1 year 1,386 1,255 In 1 to 2 years 1,366 894 In 2 to 3 years 1,219 975 In 3 to 4 years 1,189 959 In 4 to 5 years 1,088 896 More than 5 years 12,266 10,805 18,514 15,784 Guarantees Guarantee of sublease for US property (expires 2040) 149 149 Guarantees of certain obligations of Grain LNG (expire up to 2025) 31 33 Guarantees of certain obligations for construction of HVDC West Coast Link (expected expiry 2059) 84 85 Guarantees of certain obligations of National Grid North Sea Link Limited (various expiry dates) 569 584 Guarantees of certain obligations of St William Homes LLP (various expiry dates) 44 53 Guarantees of certain obligations of National Grid IFA 2 Limited (expected expiry 2022) 130 170 Guarantees of certain obligations of National Grid Viking Link Limited (expected expiry 2024) 1,177 1,276 Other guarantees and letters of credit (various expiry dates) 380 486 2,564 2,836 1. Included within future capital expenditure is £205 million (2021: £186 million) pertaining to the UK Gas Transmission business. 2. Energy purchase commitments relate to contractual commitments to purchase electricity or gas that are used to satisfy physical delivery requirements to our customers or for energy that we use ourselves (i.e. normal purchase, sale or usage) and hence are accounted for as ordinary purchase contracts (see note 32(f)). Details of commodity contract derivatives that do not meet the normal purchase, sale or usage criteria, and hence are accounted for as derivative contracts, are shown in note 17(b). Through the ordinary course of our operations, we are party to various litigation, claims and investigations. We do not expect the ultimate resolution of any of these proceedings to have a material adverse effect on our results of operations, cash flows or financial position. Contingent assets In September 2021, a fire at the IFA interconnector station in Sellindge, Kent caused significant damage to infrastructure on site. This incident has resulted in claims under the Group’s insurance policy for the rebuild cost of the damaged property and lost revenue arising from the business interruption. The Group believes that a favourable outcome is probable. However, the contingent asset has not been recognised as a receivable at 31 March 2022 because receipt of the amount is dependent on the outcome of the reinsurers formally agreeing liability and signing off on the investigation report. As at 31 March 2022, the investigation report is with the reinsurers for review and the final amount and timing of any insurance proceeds is not known with certainty.

Related party transactions

Related party transactions	12 Months Ended
	Mar. 31, 2022
Related party transactions [abstract]
Related party transactions	31. Related party transactions Related parties include joint ventures, associates, investments and key management personnel. The following significant transactions with related parties were in the normal course of business. Amounts receivable from and payable to related parties are due on normal commercial terms: 2022 2021 2020 £m £m £m Sales: Goods and services supplied to a pension plan 3 3 5 Sales: Goods and services supplied to joint ventures¹ 284 79 101 Sales: Goods and services supplied to associates² — 1 33 Purchases: Goods and services received from joint ventures³ 19 35 61 Purchases: Goods and services received from associates³ 41 43 56 Receivable from joint ventures⁴ 43 263 255 Receivable from associates 1 — 1 Payable to joint ventures 5 247 17 — Payable to associates 4 3 4 Interest income from joint ventures — — 2 Interest income from associates — — 8 Dividends received from joint ventures 6 123 49 34 Dividends received from associates 7 35 32 41 1. During the year, £74 million of sales were made to Emerald Energy Venture LLC (2021: £50 million; 2020: £21 million) and a further £7 million (2021: £6 million; 2020; £32 million) of sales were made to NGET/SPT Upgrades Limited. Prior to the Group’s disposal of its equity interest in St William Homes LLP on 15 March 2022, a further £202 million (2021: £14 million; 2020: £38 million) of property sites were sold to St William Homes LLP. 2. In previous years, sales related to transactions with Quadgas, until the date it ceased to be a related party following the disposal of our 39% stake in June 2019 (see note 10) and included income of £31 million in 2020 relating to a Transitional Service Agreement following the sale of the UK Gas Distribution business to Quadgas. 3. During the year, the Group received goods and services from a number of US associates, both for the transportation of gas and for pipeline services in the US, most notably, £38 million (2021: £41 million; 2020: £31 million) of purchases from Millennium Pipeline Company LLC. The Group purchased assets of £18 million (2021: £17 million; 2020: £nil) from BritNed Development Limited. The Group also purchased assets of £0.3 million (2021: £5 million; 2020: £58 million) from NGET/SPT Upgrades Limited (a joint venture). 4. Amounts receivable from joint ventures include £33 million (2021: £19 million; 2020: £nil) from Emerald Energy Venture LLC. Amounts receivable in comparative periods include amounts due from St William Homes LLP, which is no longer a related party of the Group (2021: £241 million; 2020: £242 million). 5. Amounts payable to joint ventures include £223 million due to Bight Wind Holdings LLC, NGV’s joint venture with RWE Renewables, in respect of a capital call to NGV following the successful auction of six seabed leases in New York. 6. Includes dividends of £39 million (2021: £18 million; 2020: £25 million) received from BritNed Development Limited and £77 million (2021: £25 million; 2020: £8 million) from Nemo Link Limited. 7. Includes dividends of £34 million (2021: £31 million; 2020: £32 million) received from Millennium Pipeline Company LLC.

Financial risk management

Financial risk management	12 Months Ended
	Mar. 31, 2022
Financial Instruments [Abstract]
Financial risk management	32. Financial risk management Our activities expose us to a variety of financial risks including credit risk, liquidity risk, capital risk, currency risk, interest rate risk, inflation risk and commodity price risk. Our risk management programme focuses on the unpredictability of financial markets and seeks to minimise potential volatility of financial performance from these risks. We use financial instruments, including derivative financial instruments, to manage these risks. Risk management related to financing activities is carried out by a central treasury department under policies approved by the Finance Committee of the Board. The objective of the treasury department is to manage funding and liquidity requirements, including managing associated financial risks, to within acceptable boundaries. The Finance Committee provides written principles for overall risk management, and written policies covering the following specific areas: foreign exchange risk, interest rate risk, credit risk, liquidity risk, use of derivative financial instruments and non-derivative financial instruments, and investment of excess liquidity. The Finance Committee has delegated authority to administer the commodity price risk policy and credit policy for US‑based commodity transactions to the Energy Procurement Risk Management Committee and the National Grid USA Board of Directors. We have exposure to the following risks, which are described in more detail below: • credit risk; • liquidity risk; • currency risk; • interest rate risk; • commodity price risk; and • capital risk. Where appropriate, derivatives and other financial instruments used for hedging currency and interest rate risk exposures are formally designated as fair value, cash flow or net investment hedges as defined in IFRS 9. Hedge accounting allows the timing of the profit or loss impact of qualifying hedging instruments to be recognised in the same reporting period as the corresponding impact of hedged exposures. To qualify for hedge accounting, documentation is prepared specifying the risk management objective and strategy, the component transactions and methodology used for measurement of effectiveness. 32. Financial risk management continued Hedge accounting relationships are designated in line with risk management activities further described below. The categories of hedging entered into are as follows: • currency risk arising from our forecasted foreign currency transactions (capital expenditure or revenues) is designated in cash flow hedges; • currency risk arising from our net investments in foreign operations is designated in net investment hedges; and • currency and interest rate risk arising from borrowings are designated in cash flow or fair value hedges. Critical terms of hedging instruments and hedged items are transacted to match on a 1:1 ratio by notional values. Hedge ineffectiveness can nonetheless arise from inherent differences between derivatives and non-derivative instruments and other market factors including credit, correlations, supply and demand, and market volatilities. Ineffectiveness is recognised in the remeasurements component of finance income and costs (see note 6). Hedge accounting is discontinued when a hedging relationship no longer qualifies for hedge accounting. Certain hedging instrument components are treated separately as costs of hedging with the gains and losses deferred in a component of other equity reserves and released systematically into profit or loss to correspond with the timing and impact of hedged exposures, or released in full to finance costs upon an early discontinuation of a hedging relationship. Refer to sections (c) currency risk and (d) interest rate risk below for further details on hedge accounting. (a) Credit risk We are exposed to the risk of loss resulting from counterparties’ default on their commitments including failure to pay or make a delivery on a contract. This risk is inherent in our commercial business activities. Exposure arises from derivative financial instruments, deposits with banks and financial institutions, trade receivables and committed transactions with wholesale and retail customers. Treasury credit risk Counterparty risk arises from the investment of surplus funds and from the use of derivative financial instruments. As at 31 March 2022, the following limits were in place for investments and derivative financial instruments held with banks and financial institutions: Maximum limit Long-term limit Triple ‘A’ G7 sovereign entities (AAA) 2,708 2,031 Triple ‘A’ vehicles (AAA) 500 — Triple ‘A’ range institutions and non-G7 sovereign entities (AAA) 2,462 1,847 Double ‘A+’ G7 sovereign entities (AA+) 2,462 1,847 Double ‘A’ range institutions (AA) 1,477 to 1,970 1,108 to 1,477 Single ‘A’ range institutions (A) 492 to 985 369 to 739 The maximum limit applies to all transactions, including long-term transactions. The long-term limit applies to transactions which mature in more than 12 months’ time. As at 31 March 2022 and 2021, we had a number of exposures to individual counterparties. In accordance with our treasury policies, counterparty credit exposure utilisations are monitored daily against the counterparty credit limits. Counterparty credit ratings and market conditions are reviewed continually with limits being revised and utilisation adjusted, if appropriate. Management does not expect any significant losses from non-performance by these counterparties. Further information on financial investments subject to impairment provisioning is included in note 15. Commodity credit risk The credit policy for US-based commodity transactions is owned by the Finance Committee to the Board, which establishes controls and procedures to determine, monitor and minimise the credit exposure to counterparties. Wholesale and retail credit risk Our principal commercial exposure in the UK is governed by the credit rules within the regulated codes: Uniform Network Code and Connection and Use of System Code. These set out the level of credit relative to the RAV for each credit rating. In the US, we are required to supply electricity and gas under state regulations. Our policies and practices are designed to limit credit exposure by collecting security deposits prior to providing utility services, or after utility services have commenced if certain applicable regulatory requirements are met. Collection activities are managed on a daily basis. Sales to retail customers are usually settled in cash, cheques, electronic bank payments or by using major credit cards. We are committed to measuring, monitoring, minimising and recording counterparty credit risk in our wholesale business. The utilisation of credit limits is regularly monitored, and collateral is collected against these accounts when necessary. In March 2020, the Group’s US distribution business temporarily ceased certain cash collection and termination activities in response to regulatory instructions following the COVID-19 pandemic. At the time this resulted in the recognition of expected credit losses. In the year ended 31 March 2022, collection activities resumed in New England and New York and are supported by certain government COVID funding programmes, which has been factored into the assessment of expected credit losses for the year (see note 19 for further details). 32. Financial risk management continued (a) Credit risk continued Offsetting financial assets and liabilities The following tables set out our financial assets and liabilities which are subject to offset and to enforceable master netting arrangements or similar agreements. The tables show the amounts which are offset and reported net in the statement of financial position. Amounts which cannot be offset under IFRS, but which could be settled net under terms of master netting arrangements if certain conditions arise, and with collateral received or pledged, are shown to present National Grid’s net exposure. Financial assets and liabilities on different transactions would only be reported net in the balance sheet if the transactions were with the same counterparty, a currently enforceable legal right of offset exists, and the cash flows were intended to be settled on a net basis. Amounts which do not meet the criteria for offsetting on the statement of financial position, but could be settled net in certain circumstances, principally relate to derivative transactions under ISDA agreements, where each party has the option to settle amounts on a net basis in the event of default of the other party. Commodity contract derivatives that have not been offset on the balance sheet may be settled net in certain circumstances under ISDA or North American Energy Standards Board (NAESB) agreements. For bank account balances and bank overdrafts, there are no ‘Gross amounts offset’ under cash pooling arrangements (2021: £nil). Our UK bank accounts for National Grid subsidiaries previously participated in GBP, EUR and USD Composite Accounting System overdraft facilities subject to offsetting gross and net overdraft limits. EUR and USD offsetting arrangements were discontinued in the prior year and GBP offsetting arrangements have no impact as at 31 March 2022. In the US, no offsetting arrangements exist, and cash transactions are settled through Service Company bank accounts with subsequent intercompany payables and receivables reported by subsidiaries with the Service Company. The gross amounts offset for trade payables and receivables, which are subject to general terms and conditions, are insignificant. Related amounts At 31 March 2022 Gross Gross Net amount Financial instruments Cash Net amount Assets Financing derivatives 298 — 298 (136) (55) 107 Commodity contract derivatives 289 — 289 (8) (50) 231 587 — 587 (144) (105) 338 Liabilities Financing derivatives (991) — (991) 136 771 (84) Commodity contract derivatives (22) — (22) 8 3 (11) (1,013) — (1,013) 144 774 (95) (426) — (426) — 669 243 Related amounts At 31 March 2021 Gross carrying amounts £m Gross Net amount presented in statement of financial position £m Financial instruments £m Cash collateral received/ pledged £m Net amount £m Assets Financing derivatives 942 — 942 (234) (561) 147 Commodity contract derivatives 57 — 57 (8) — 49 999 — 999 (242) (561) 196 Liabilities Financing derivatives (767) — (767) 234 467 (66) Commodity contract derivatives (132) — (132) 8 4 (120) (899) — (899) 242 471 (186) 100 — 100 — (90) 10 32. Financial risk management continued (b) Liquidity risk Our policy is to determine our liquidity requirements by the use of both short-term and long-term cash flow forecasts. These forecasts are supplemented by a financial headroom analysis which is used to assess funding requirements for at least a 24-month period and maintain adequate liquidity for a continuous 12-month period. We believe our contractual obligations, including those shown in commitments and contingencies in note 30, can be met from existing cash and investments, operating cash flows and other financing that we reasonably expect to be able to secure in the future, together with the use of committed facilities if required. Our debt agreements and banking facilities contain covenants, including those relating to the periodic and timely provision of financial information by the issuing entity, restrictions on disposals and financial covenants, such as restrictions on the level of subsidiary indebtedness and interest coverage. Failure to comply with these covenants, or to obtain waivers of those requirements, could in some cases trigger a right, at the lender’s discretion, to require repayment of some of our debt and may restrict our ability to draw upon our facilities or access the capital markets. The following is a payment profile of our financial liabilities and derivatives: At 31 March 2022 Less than £m 1 to 2 2 to 3 More than Total Non-derivative financial liabilities Borrowings, excluding lease liabilities (11,589) (1,322) (2,468) (28,119) (43,498) Interest payments on borrowings¹ (970) (928) (883) (12,525) (15,306) Lease liabilities (132) (96) (79) (366) (673) Other non-interest-bearing liabilities (3,979) (336) — — (4,315) Contingent consideration (37) (8) — — (45) Derivative financial liabilities Financing derivatives – receipts² 3,149 1,008 2,075 4,726 10,958 Financing derivatives – payments² (3,401) (1,189) (2,336) (5,468) (12,394) Commodity contract derivatives – receipts² 1 1 — — 2 Commodity contract derivatives – payments² (29) 2 (1) — (28) Derivative financial assets Financing derivatives – receipts² 4,512 316 1,427 464 6,719 Financing derivatives – payments² (4,405) (282) (1,313) (405) (6,405) Commodity contract derivatives – receipts² 234 37 3 — 274 Commodity contract derivatives – payments² (52) (8) (3) — (63) (16,698) (2,805) (3,578) (41,693) (64,774) At 31 March 2021 Less than 1 year £m 1 to 2 2 to 3 years £m More than 3 years £m Total £m Non-derivative financial liabilities Borrowings, excluding lease liabilities (3,350) (1,690) (806) (25,562) (31,408) Interest payments on borrowings¹ (810) (755) (731) (12,018) (14,314) Lease liabilities (118) (108) (90) (599) (915) Other non-interest-bearing liabilities (3,207) (350) — — (3,557) Contingent consideration (40) (24) — — (64) Derivative financial liabilities Financing derivatives – receipts² 3,773 749 451 4,326 9,299 Financing derivatives – payments² (3,899) (877) (533) (5,153) (10,462) Commodity contract derivatives – receipts² 12 — — — 12 Commodity contract derivatives – payments² (83) (23) (14) (12) (132) Derivative financial assets Financing derivatives – receipts² 2,162 926 833 1,789 5,710 Financing derivatives – payments² (1,700) (834) (780) (1,536) (4,850) Commodity contract derivatives – receipts² 21 4 1 1 27 Commodity contract derivatives – payments² (21) (4) (2) — (27) (7,260) (2,986) (1,671) (38,764) (50,681) 1. The interest on borrowings is calculated based on borrowings held at 31 March without taking account of future issues. Floating rate interest is estimated using a forward interest rate curve as at 31 March. Payments are included on the basis of the earliest date on which the Company can be required to settle. 2. The receipts and payments line items for derivatives comprise gross undiscounted future cash flows, after considering any contractual netting that applies within individual contracts. Where cash receipts and payments within a derivative contract are settled net, and the amount to be received/(paid) exceeds the amount to be paid/(received), the net amount is presented within derivative receipts/(payments). 32. Financial risk management continued (c) Currency risk National Grid operates internationally with mainly pound sterling as the functional currency for the UK companies and US dollar for the US businesses. Currency risk arises from three major areas: funding activities, capital investment and related revenues, and holdings in foreign operations. This risk is managed using financial instruments including derivatives as approved by policy, typically cross-currency interest rate swaps, foreign exchange swaps and forwards. Funding activities – our policy is to borrow in the most advantageous market available. Foreign currency funding gives rise to risk of volatility in the amount of functional currency cash to be repaid. This risk is reduced by swapping principal and interest back into the functional currency of the issuer. All foreign currency debt and transactions are hedged except where they provide a natural offset to assets elsewhere in the Group. Capital investment and related revenues – capital projects often incur costs or generate revenues in a foreign currency, most often euro transactions done by the UK business. Our policy for managing foreign exchange transaction risk is to hedge contractually committed foreign currency cash flows over a prescribed minimum size, typically by buying euro forwards to hedge future expenditure, and selling euro forwards to hedge future revenues. For hedges of forecast cash flows our policy is to hedge a proportion of highly probable cash flows. Holdings in foreign operations – we are exposed to fluctuations on the translation into pounds sterling of our foreign operations. The policy for managing this translation risk is to issue foreign currency debt or to replicate foreign debt using derivatives that pay cash flows in the currency of the foreign operation. The primary managed exposure arises from dollar denominated assets and liabilities held by our US operations, with a smaller euro exposure in respect of joint venture investments. Derivative financial instruments were used to manage foreign currency risk as follows: 2022 2021 Sterling Euro Dollar Other Total Sterling £m Euro £m Dollar £m Other £m Total £m Cash and cash equivalents 111 — 93 — 204 63 — 94 — 157 Financial investments 1,725 — 1,420 — 3,145 1,215 — 1,127 — 2,342 Borrowings (22,910) (7,052) (14,118) (1,385) (45,465) (12,210) (5,351) (12,660) (999) (31,220) Pre-derivative position (21,074) (7,052) (12,605) (1,385) (42,116) (10,932) (5,351) (11,439) (999) (28,721) Derivative effect (1,378) 6,849 (7,570) 1,406 (693) (826) 5,459 (5,494) 1,036 175 Net debt position (22,452) (203) (20,175) 21 (42,809) (11,758) 108 (16,933) 37 (28,546) The exposure to dollars largely relates to our net investment hedge activities and exposure to euros largely relates to hedges for our future non-sterling capital expenditure. The currency exposure on other financial instruments is as follows: 2022 2021 Sterling Euro Dollar Other Total Sterling £m Euro £m Dollar £m Other £m Total £m Trade and other receivables 407 — 1,788 — 2,195 282 — 1,387 — 1,669 Trade and other payables (1,459) — (2,554) — (4,013) (1,207) — (1,878) — (3,085) Other non-current liabilities (90) — (253) — (343) (77) — (288) — (365) The carrying amounts of other financial instruments are denominated in the above currencies, which in most instances are the functional currency of the respective subsidiaries. Our exposure to dollars is due to activities in our US subsidiaries. We do not have any other significant exposure to currency risk on these balances. Hedge accounting for currency risk Where available, derivatives transacted for hedging are designated for hedge accounting. Economic offset is qualitatively determined because the critical terms (currency and volume) of the hedging instrument match the hedged exposure. If a forecast transaction was no longer expected to occur, the cumulative gain or loss previously reported in equity would be transferred to the income statement. This has not occurred in the current or comparative years. Cash flow hedging of currency risk of capital expenditure and revenues is designated as hedging the exposure to movements in the spot translation rates only. The timing of forecasted transactions is not designated as a hedged risk. Gains and losses on hedging instruments arising from forward points and foreign currency basis spreads are excluded from designation and are recognised immediately in profit or loss, along with any hedge ineffectiveness. On recognition of the hedged purchase or sale in the financial statements, the associated hedge gains and losses, deferred in the cash flow hedge reserve in other equity reserves, are transferred out of reserves and included with the recognition of the underlying transaction. Where a non-financial asset or a non-financial liability results from a forecast transaction or firm commitment being hedged, the amounts deferred in reserves are included directly in the initial measurement of that asset or liability. Net investment hedging is also designated as hedging the exposure to movements in spot translation rates only: spot-related gains and losses on hedging instruments are presented in the cumulative translation reserve within other equity reserves to offset gains or losses on translation of the hedged balance sheet exposure. Any ineffectiveness is recognised immediately in the income statement. Amounts deferred in the cumulative translation reserve with respect to net investment hedges are subsequently recognised in the income statement in the event of disposal of the overseas operations concerned. Any remaining amounts deferred in the cost of hedging reserve are also released to the income statement. Hedges of foreign currency funding are designated as cash flow hedges or fair value hedges of forward exchange risk (hedging both currency and interest rate risk together, where applicable). Gains and losses arising from foreign currency basis spreads are excluded from designation and are treated as a cost of hedging, deferred initially in other equity reserves and released into profit or loss over the life of the hedging relationship. Hedge accounting for funding is described further in the interest rate risk section below. 32. Financial risk management continued (d) Interest rate risk National Grid’s interest rate risk arises from our long-term borrowings. Our interest rate risk management policy is to seek to minimise total financing costs (being interest costs and changes in the market value of debt). Hedging instruments principally consist of interest rate and cross-currency swaps that are used to translate foreign currency debt into functional currency and to adjust the proportion of fixed-rate and floating-rate in the borrowings portfolio to within a range set by the Finance Committee of the Board. The benchmark interest rates hedged are currently based on LIBOR for USD and Sterling Overnight Index Average (SONIA) for GBP. LIBOR is being replaced as an interest rate benchmark by alternative reference rates in certain currencies including our functional currencies, USD and GBP, and foreign currencies in which we operate. This impacts contracts including financial liabilities that pay LIBOR-based cash flows, and derivatives that receive or pay LIBOR-based cash flows. The change in benchmark also affects discount rates which will impact the valuations of certain liabilities. We have disclosed our exposure to LIBOR on our derivative portfolio in note 17, on our borrowings in note 21 and on our hedging arrangements in note 32(e). We are managing the risk by transitioning LIBOR cash flows to alternative reference rates on our affected contracts in line with the relevant jurisdictions. The migration project is underway, with all affected contracts where we previously paid or received GBP LIBOR amended in the year to 31 March 2022 (see note 21). The Finance Committee of the Board have delegated to the treasury department the authority to determine which benchmarks are the most appropriate. A combination of LIBOR and the successor benchmarks, primarily GBP SONIA and USD Secured Overnight Financing Rate (SOFR) will be used in the portfolio during the migration period. We also consider inflation risk and hold some inflation-linked borrowings. We believe that these provide a partial economic offset to the inflation risk associated with our UK inflation-linked revenues. The table in note 21 sets out the carrying amount, by contractual maturity, of borrowings that are exposed to interest rate risk before taking into account interest rate swaps. Net debt was managed using derivative financial instruments to hedge interest rate risk as follows: 2022 2021 Fixed rate £m Floating rate £m Inflation linked £m Other 1 £m Total £m Fixed rate £m Floating rate £m Inflation linked £m Other 1 £m Total £m Cash and cash equivalents 82 118 — 4 204 64 67 — 26 157 Financial investments — 3,107 — 38 3,145 — 2,309 — 33 2,342 Borrowings (30,616) (10,484) (4,365) — (45,465) (23,163) (1,762) (6,295) — (31,220) Pre-derivative position (30,534) (7,259) (4,365) 42 (42,116) (23,099) 614 (6,295) 59 (28,721) Derivative effect 2,860 (3,366) (187) — (693) 2,869 (2,511) (183) — 175 Net debt position (27,674) (10,625) (4,552) 42 (42,809) (20,230) (1,897) (6,478) 59 (28,546) 1. Represents financial instruments which are not directly affected by interest rate risk, such as investments in equity or other similar financial instruments. Hedge accounting for interest rate risk Borrowings paying variable or floating-rates expose National Grid to cash flow interest rate risk, partially offset by cash held at variable rates. Where a hedging instrument results in paying a fixed-rate, it is designated as a cash flow hedge because it has reduced the cash flow volatility of the hedged borrowing. Changes in the fair value of the derivative are initially recognised in other comprehensive income as gains or losses in the cash flow hedge reserve, with any ineffective portion recognised immediately in the income statement. Borrowings paying fixed-rates expose National Grid to fair value interest rate risk. Where the hedging instrument pays a floating-rate, it is designated as a fair value hedge because it has reduced the fair value volatility of the borrowing. Changes in the fair value of the derivative and changes in the fair value of the hedged item in relation to the risk being hedged are both adjusted on the balance sheet and offset in the income statement to the extent the fair value hedge is effective, with the residual difference remaining as ineffectiveness. Both types of hedges are designated as hedging the currency and interest rate risk arising from changes in forward points. Amounts accumulated in the cash flow hedge reserve (cash flow hedges only) and the deferred cost of hedging reserve (both cash flow and fair value hedges) are reclassified from reserves to the income statement on a systematic basis as hedged interest expense is recognised. Adjustments made to the carrying value of hedged items in fair value hedges are similarly released to the income statement to match the timing of the hedged interest expense. When hedge accounting is discontinued, any remaining cumulative hedge accounting balances continue to be released to the income statement to match the impact of outstanding hedged items. Any remaining amounts deferred in the cost of hedging reserve are released immediately to the income statement as finance costs. The Group early-adopted Phase I of IFRS Interest Rate Benchmark Reform amendments related to hedge accounting with effect from 1 April 2019, and Phase II with effect from 1 April 2020. The amendments impact our fair value hedging relationships where derivative cash flows will have been transitioned from paying LIBOR to paying an alternative reference rate. The hedged risk must be re-documented to reflect this, and allow existing hedge designations to continue unchanged during the period of uncertainty relating to the timing and method of benchmark migrations. This process has been completed for sterling LIBOR contracts but remains in progress for US dollar contracts. The amendments will be applied until the earliest point in time of the Group’s contracts that reference LIBOR being amended, the hedging relationship being formally discontinued or formal market conventions ending uncertainty being published and widely adopted. If amended cash flows do not cause a hedging relationship to be discontinued, then the amendments will cease to be applied only when that relationship is discontinued under IFRS 9. The IFRS amendments impact fair value and cash flow hedges of interest rate risk and related hedging instruments, and certain net investment hedges that use cross-currency interest rate swaps to pay a foreign currency floating rate and receive a functional currency floating rate. The notional values of hedging instruments, for each type of hedging relationship impacted, are shown in the hedge accounting tables in note 32(e). These amounts also correspond to the exposures designated as hedged. 32. Financial risk management continued (e) Hedge accounting In accordance with the requirements of IFRS 7, certain additional information about hedge accounting is disaggregated by risk type and hedge designation type in the tables below: Year ended 31 March 2022 Fair value hedges of foreign currency and interest rate risk Cash flow hedges of foreign currency and interest rate risk Cash flow hedges of foreign currency risk Net investment hedges Consolidated statement of comprehensive income Net gains/(losses) in respect of: Cash flow hedges — (103) (1) — Cost of hedging (7) 16 — (7) Transferred to profit or loss in respect of: Cash flow hedges — 43 — — Cost of hedging 1 — — (2) Consolidated statement of changes in equity Other equity reserves – cost of hedging balances (15) (16) — (3) Consolidated statement of financial position Derivatives – carrying value of hedging instruments ¹ Assets – current — — 1 10 Assets – non-current 49 67 1 82 Liabilities – current (21) (22) (37) (16) Liabilities – non-current (310) (303) (8) — Profiles of the significant timing, price and rate information of hedging instruments Maturity range Jul 2022 – Sep 2044 Jun 2022 – Nov 2040 Apr 2022 – Feb 2027 Sep 2022 – Sep 2027 Spot foreign exchange range: GBP:USD n/a 1.30 – 1.66 1.34 – 1.41 1.22 – 1.34 GBP:EUR 1.11 – 1.24 1.08 – 1.24 1.04 – 1.19 1.18 EUR:USD 1.13 – 1.17 1.13 – 1.15 n/a n/a Interest rate range: GBP SONIA +84bps/+374bps 0.976% – 7.410% n/a n/a USD LIBOR +68bps/+115bps 2.095% – 3.864% n/a n/a 1. The use of derivatives may entail a derivative transaction qualifying for more than one hedge type designation under IFRS 9. Therefore, the derivative amounts in the table above are grossed up by hedge type, whereas they are presented net at an instrument level in the statement of financial position. 32. Financial risk management continued (e) Hedge accounting continued Year ended 31 March 2021 Fair value hedges of foreign currency and interest rate risk Cash flow hedges of Cash flow hedges of Net investment hedges Consolidated statement of comprehensive income Net losses in respect of: Cash flow hedges — 14 (14) — Cost of hedging (15) (24) — 50 Transferred to profit or loss in respect of: Cash flow hedges — 56 — — Cost of hedging 1 2 — — Consolidated statement of changes in equity Other equity reserves – cost of hedging balances (11) (30) — 6 Consolidated statement of financial position Derivatives – carrying value of hedging instruments¹ Assets – current — 10 2 5 Assets – non-current 187 59 1 140 Liabilities – current — (12) (24) (17) Liabilities – non-current (113) (255) (22) — Profiles of the significant timing, price and rate information of hedging instruments Maturity range Jan 2023 – Jan 2043 Sep 2021 – Nov 2040 Apr 2021 – Feb 2027 Mar 2022 – Sep 2027 Spot foreign exchange range: GBP:USD 1.64 1.30 – 1.66 1.31 – 1.41 1.22 – 1.40 GBP:EUR 1.11 – 1.24 1.08 – 1.24 1.04 – 1.29 1.15 – 1.16 EUR:USD 1.13 – 1.17 1.13 – 1.14 n/a n/a Interest rate range: GBP LIBOR +30bps/+408bps 0.976% – 5.845% n/a n/a USD LIBOR –68bps/+115bps 2.513% – 3.864% n/a n/a 1. The use of derivatives may entail a derivative transaction qualifying for more than one hedge type designation under IFRS 9. Therefore, the derivative amounts in the table above are grossed up by hedge type, whereas they are presented net at an instrument level in the statement of financial position. 32. Financial risk management continued (e) Hedge accounting continued The following tables show the effects of hedge accounting on financial position and year-to-date performance for each type of hedge. These tables also present notional values of hedging instruments (and equal hedged exposures) impacted by IFRS 9 Interest Rate Benchmark Reform amendments. (i) Fair value hedges of foreign currency and interest rate risk on recognised borrowings: As at 31 March 2022 Balance of fair value hedge adjustments in borrowings Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings 1,2 (3,362) 437 (55) 340 (301) 39 1. The carrying value of the hedged borrowings is £2,966 million, of which £nil is current and £2,966 million is non-current. 2. Included within the hedging instrument notional balance is £2,556 million impacted by Interest Rate Benchmark Reform amendments with £806 million still to be transitioned. As at 31 March 2021 Balance of fair value hedge adjustments in borrowings Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings 1,2 (2,755) 121 (85) 153 (127) 26 1. The carrying value of the hedged borrowings was £2,714 million, of which £nil was current and £2,714 million was non-current.

Borrowing facilities

Borrowing facilities	12 Months Ended
	Mar. 31, 2022
Disclosure of detailed information about borrowings [abstract]
Borrowing facilities	33. Borrowing facilities To support our liquidity requirements and provide backup to commercial paper and other borrowings, we agree committed credit facilities with financial institutions over and above the value of borrowings that may be required. These committed credit facilities are undrawn. At 31 March 2022, we had bilateral committed credit facilities of £5,978 million (2021: £5,410 million). In addition, we had committed credit facilities from syndicates of banks of £936 million at 31 March 2022 (2021: £115 million). An analysis of the maturity of these undrawn committed facilities is shown below: 2022 2021 £m £m Undrawn committed borrowing facilities expiring: Less than 1 year — — In 1 to 2 years 936 1,668 In 2 to 3 years 4,373 534 In 3 to 4 years 1,605 1,718 In 4 to 5 years — 1,605 More than 5 years — — 6,914 5,525 Of the unused facilities at 31 March 2022, £6,823 million (2021: £5,410 million) is available for liquidity purposes, while £91 million (2021: £115 million) is available as backup to specific US borrowings. The increase in total facility positions reflects the increased size of the Group following the acquisition of WPD. £845 million of the undrawn syndicated facilities due to mature in one to two years were renegotiated between 1 April and 19 May 2022, with no uplift in the amount and a new expiry date of May 2025. Included in the table above within three to four years is a facility of £350 million related to National Grid Gas plc, a company treated as held for sale. In addition, we have the following facilities which are not included in the table above: • for the separately regulated business of National Grid Electricity System Operator Limited, the Group has a facility of £550 million (2021: £550 million). This facility is not available as Group general liquidity support; • the Group continues to have access to Export Credit Agreements (ECAs) funding specific projects totalling £1,396 million (2021: £1,345 million), of which £489 million (2021: £446 million) is undrawn; and • the Group entered into a loan facility in relation to the acquisition of WPD (see note 37) of £8,250 million (31 March 2021: £8,250 million) to finance the consideration, of which £8,179 million has been drawn since the year end with no further drawdown available (31 March 2021: undrawn). The bridge facility allows for the extension of the facility maturity date up to September 2023 but includes a requirement that the proceeds of the planned sales of NECO and the UK Gas Transmission business are applied to repay the facility.

Subsidiary undertakings, joint

Subsidiary undertakings, joint ventures and associates	12 Months Ended
	Mar. 31, 2022
Interests In Other Entities [Abstract]
Subsidiary undertakings, joint ventures and associates	16. Investments in joint ventures and associates Investments in joint ventures and associates represent businesses we do not control but over which we exercise joint control or significant influence. They are accounted for using the equity method. A joint venture is an arrangement established to engage in economic activity, which the Group jointly controls with other parties and has rights to a share of the net assets of the arrangement. An associate is an entity which is neither a subsidiary nor a joint venture, but over which the Group has significant influence. 2022 2021 Associates Joint Total Associates £m Joint ventures £m Total £m Share of net assets at 1 April 229 638 867 341 654 995 Exchange adjustments 6 19 25 (22) (36) (58) Additions 17 469 486 6 75 81 Share of post-tax results for the year 43 49 92 30 28 58 Share of other comprehensive income of associates, net of tax 1 — 1 1 — 1 Dividends received (35) (123) (158) (31) (49) (80) Disposals — (50) (50) — — — Other movements¹ 16 (41) (25) (96) (34) (130) Share of net assets at 31 March 277 961 1,238 229 638 867 1. Other movements relate to tax liabilities for US and certain UK associates and joint ventures which are borne by the Group and the elimination of profits arising from sales to the Group’s share of joint ventures. Within associates, the other movements in the year ended 31 March 2021 primarily relates to the reclassification of the Group’s investment in Sunrun from an investment in an associate to financial investments. A list of joint ventures and associates including the name and proportion of ownership is provided in note 34. Transactions with and outstanding balances with joint ventures and associates are shown in note 31. The joint ventures and associates have no significant contingent liabilities to which the Group is exposed, and the Group has no significant contingent liabilities in relation to its interests in the joint ventures and associates. The Group has capital commitments of £714 million (2021: £141 million) in relation to joint ventures and associates. On 15 March 2022, the Group disposed of its entire 50% interest in St William Homes LLP to The Berkeley Group for cash consideration of £413 million. The receipt of cash has been recognised within net cash used in investing activities within the cash flow statement. The Group recognised a gain on disposal of £228 million within Other operating income and costs and released to revenue deferred income of £189 million which related to deferred profits related to previous property sales to St William Homes LLP. The gain on disposal and the release of deferred income are both classified as exceptional in the year (see note 5). The following table describes the Group’s material joint ventures and associates at 31 March 2022: Joint venture % stake BritNed Development Limited 1 50 % BritNed is a joint venture with the Dutch transmission system operator, TenneT, and operates the subsea electricity link between Great Britain and the Netherlands, commissioned in 2011. Nemo Link Limited 1 50 % Nemo is a joint venture with the Belgian transmission operator, Elia, and is a subsea electricity interconnector between Great Britain and Belgium, which became operational on 31 January 2019. Emerald Energy Venture LLC 51 % Emerald is a joint venture with Washington State Investment Board and builds and operates wind and solar assets. Emerald was acquired on 11 July 2019. Bight Wind Holdings LLC 27.3 % Bight Wind is a joint venture with RWE Renewables. Following the successful win at auction of six seabed leases in northeastern US on 25 February 2022, Bight Wind will commence the development of an offshore wind project which will play a key role in supplying clean energy to customers in New York. At 31 March 2022, the Group has an amount payable to Bight Wind of £223 million in respect of a capital call to the Group which is payable in April 2022. The assets, liabilities and results of Bight Wind will become material to the Group upon recognition of the seabed lease in the year ending 31 March 2023. Material associate % stake Millennium Pipeline Company LLC 26.25 % Millennium Pipeline Company LLC is an associate that owns a natural gas pipeline from southern New York to the Lower Hudson Valley. 1. BritNed and Nemo have reporting periods ending on 31 December with monthly management reporting information provided to National Grid. 16. Investments in joint ventures and associates continued Summarised financial information as at 31 March, together with the carrying amount of material investments, is as follows: BritNed Development Nemo Link Limited Emerald Energy Millennium Pipeline Company LLC 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Statement of financial position Non-current assets 390 409 515 536 1,070 559 800 795 Cash and cash equivalents 77 47 7 31 134 112 33 27 All other current assets 10 24 7 8 8 12 29 24 Non-current liabilities (52) (50) (34) (30) (182) (182) (237) (256) Non-current financial liabilities (29) (31) — — (310) (104) — — Current liabilities (15) (22) (33) (19) (66) (25) (45) (38) Current financial liabilities — — — — (23) (2) — — Net assets 381 377 462 526 631 370 580 552 Group’s ownership interest 191 189 231 263 322 189 152 145 Group adjustment: elimination — — — — (49) (23) — — Carrying amount of the Group’s investment 191 189 231 263 273 166 152 145 BritNed Development Nemo Link Limited Emerald Energy Millennium Pipeline Company LLC 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Income statement Revenue 131 72 148 66 25 28 200 199 Depreciation and amortisation (15) (15) (23) (24) (17) (14) (43) (43) Other costs (9) (15) (6) (6) (145) (22) (20) (21) Operating profit/(loss) 107 42 119 36 (137) (8) 137 135 Net interest expense (2) (1) (1) — (5) — (21) (18) Profit/(loss) before tax 105 41 118 36 (142) (8) 116 117 Income tax expense (20) (11) (22) (14) — — — — Profit/(loss) for the year 85 30 96 22 (142) (8) 116 117 Group’s share of profit/(loss) 43 15 48 11 (72) (4) 30 31 Group adjustment: tax credit/(charge) — — — — 19 1 (8) (9) Group’s share of post-tax results for the year 43 15 48 11 (53) (3) 22 22 While we present consolidated results in these financial statements as if we were one company, our legal structure is such that there are a number of different operating and holding companies that contribute to the overall result. This structure has evolved through acquisitions as well as regulatory requirements to have certain activities within separate legal entities. Subsidiary undertakings A list of the Group’s subsidiaries as at 31 March 2022 is given below. The entire share capital of subsidiaries is held within the Group except where the Group’s ownership percentages are shown. These percentages give the Group’s ultimate interest and therefore allow for the situation where subsidiaries are owned by partly owned intermediate subsidiaries. Where subsidiaries have different classes of shares, this is largely for historical reasons, and the effective percentage holdings given represent both the Group’s voting rights and equity holding. Shares in National Grid (US) Holdings Limited, National Grid (US) Investments 2 Limited, National Grid Hong Kong Limited, National Grid Luxembourg SARL and NGG Finance plc are held directly by National Grid plc. All other holdings in subsidiaries are owned by other subsidiaries within the Group. All subsidiaries are consolidated in the Group’s financial statements. Principal Group companies are identified in bold . These companies are incorporated and principally operate in the countries under which they are shown. All entities incorporated in the United States are taxed in the United States on their worldwide income other than where indicated in the footnotes below. Other entities are tax resident in their jurisdiction of incorporation other than where indicated in the footnotes below. Incorporated in England and Wales Registered office: 1–3 Strand, London WC2N 5EH, UK (unless stated otherwise in footnotes). Birch Sites Limited Carbon Sentinel Limited Central Networks Trustees Limited 1 Droylsden Metering Services Limited Gridcom Limited Hyder Profit Sharing Trustees Limited 1 Icelink Interconnector Limited Kelston Properties 2 Limited 1 Lattice Group Employee Benefit Trust Limited Lattice Group Limited Lattice Group Trustees Limited Meter Operator Services Limited* 1 Meter Reading Services Limited* 1 Natgrid Limited NatGrid One Limited 2 NatgridTW1 Limited 2 National Grid (US) Holdings Limited 2 National Grid (US) Investments 2 Limited 2 National Grid (US) Investments 4 Limited 2 National Grid (US) Partner 1 Limited 2 National Grid Carbon Limited National Grid Commercial Holdings Limited National Grid Distributed Energy Limited National Grid Electricity Group Trustee Limited National Grid Electricity System Operator Limited National Grid Electricity Transmission plc National Grid Energy Metering Limited National Grid Gas Holdings Limited National Grid Gas plc National Grid Grain LNG Limited National Grid Holdings Limited 2 National Grid Holdings One plc National Grid Hydrogen Limited National Grid IFA 2 Limited National Grid Interconnector Holdings Limited National Grid Interconnectors Limited National Grid International Limited 2 National Grid Metering Limited National Grid North Sea Link Limited National Grid Offshore Limited National Grid Partners Limited National Grid Plus Limited National Grid Property Holdings Limited National Grid Smart Limited National Grid Ten National Grid Thirty Six Limited National Grid Twelve Limited 2 National Grid Twenty Eight Limited National Grid Twenty Seven Limited National Grid Twenty Three Limited 2 National Grid UK Limited National Grid UK Pension Services Limited National Grid Ventures Limited National Grid Viking Link Limited National Grid William Limited NG Nominees Limited NGC Employee Shares Trustee Limited NGG Finance plc Ngrid Intellectual Property Limited NGT Two Limited Port Greenwich Limited Sheet Road Management Company Limited (51%) 3 South Wales Electricity Share Scheme Trustees Limited 1 South Western Helicopters Limited 1 Supergrid Electricity Limited Supergrid Energy Transmission Limited Supergrid Limited Thamesport Interchange Limited The National Grid Group Quest Trustee Company Limited The National Grid YouPlan Trustee Limited Transco Limited Warwick Technology Park Management Company (No 2) Limited (60.56%) 4 Western Power Distribution (East Midlands) plc 1 Western Power Distribution (South Wales) plc 1 Western Power Distribution (South West) plc 1 Western Power Distribution (West Midlands) plc 1 Western Power Distribution Holding Company Limited 1 Western Power Distribution Investments Limited 1 Western Power Distribution plc 1 Western Power Generation Limited 1 Western Power Pension Trustee Limited 1 WPD Distribution Network Holdings Limited 1 WPD Investment Holdings limited 1 WPD Island Limited 1 WPD Limited 1 WPD Midlands Limited 1 WPD Midlands Networks Contracting Limited* 1 WPD Property Investments Limited 1 WPD Share Scheme Trustees Limited 1 WPD Smart Metering Limited 1 WPD Telecoms Limited 1 WPD WEM Holdings Limited 1 WPD WEM Limited 1 WW Share Scheme Trustees Limited 1 1. Registered office: Avonbank, Feeder Road, Bristol, Avon, BS2 0TB. 2. Companies where National Grid plc has issued guarantees over the liabilities of the companies as at 31 March 2022 and for which the companies are taking the exemption from the requirements of an audit for their individual financial statements as permitted by section 479A of the Companies Act. 3. Registered office: Netley Old Hall Farm, Dorrington, Shrewsbury, United Kingdom, SY5 7JY. 4. Registered office: Shire Hall, PO Box 9, Warwick CV34 4RL, UK. * In process of strike-off. Incorporated in the US Registered office: National Registered Agents, Inc., 1209 Orange Street, Wilmington, DE 19801, USA (unless stated otherwise in footnotes). Apple River Solar, LLC Armenia Solar, LLC Ashland Solar, LLC Athens Solar, LLC Autauga Solar, LLC Banner Solar, LLC Bazile Creek Wind Farm, LLC Bee Hollow Solar, LLC Bell Plaine Solar, LLC Benevolent Solar, LLC Blaze Solar, LLC 1 Blevins Solar, LLC Blue Ridge Wind, LLC Blue Spring Solar, LLC Blues Solar, LLC Bluewater Solar, LLC Boone Solar, LLC Boston Gas Company 2 Bridges Solar, LLC British Transco Capital, Inc. 3 British Transco Finance, Inc. 3 Brock Solar, LLC Broken Bridge Corp. 4 Brook Trout Solar, LLC Burley Solar, LLC Burlington Solar, LLC Burr Ridge Wind, LLC Cage Ranch Solar II, LLC Cage Ranch Solar III, LLC Cage Ranch Solar, LLC Caldwell Solar II, LLC Caldwell Solar, LLC Canby Solar, LLC Cass Wind Farm, LLC Cattle Ridge Wind Farm 2, LLC Cedar Grove Solar, LLC Centennial Solar, LLC Clay Boswell Solar, LLC Clear Creek Solar, LLC Clermont Solar, LLC Clinton County Solar, LLC Coles Solar, LLC Compass Prairie Wind, LLC Coneflower Solar, LLC 5 Conestoga Wind, LLC Copperhead Solar, LLC Creekview Solar, LLC Crocker Wind Farm 2, LLC Dahlia Solar, LLC 5 Dakota Hills Wind Farm, LLC Day Lily Solar, LLC 5 Deatsville Solar, LLC Deer Trail Solar, LLC Dodson Creek Solar, LLC 6 Donnellson Solar, LLC Elburn Solar, LLC Eldena Solar, LLC Elk Creek Solar 2, LLC Elk Creek Solar, LLC EUA Energy Investment Corporation 2 Exie Solar, LLC Falls City Solar, LLC Fayette Solar, LLC 7 Fillmore County Solar Project, LLC Firstview Wind Farm, LLC Fort Solar, LLC Front Range Wind Farm, LLC Gardenia Solar, LLC 5 Golden Solar, LLC Goldendale Solar, LLC Goldenrod Wind Farm, LLC Goldfinch Solar, LLC Grand Junction Solar, LLC Granite State Power Link LLC 3 Grant Solar 2, LLC Grant Solar, LLC Grayson Solar, LLC Greenbrier Creek Solar, LLC Greensky Solar, LLC Greenwood Solar, LLC Grid NY LLC 8 Grindstone Wind Farm, LLC 9 Hale County Solar, LLC Hansford Energy Storage, LLC Harmony Solar ND 2, LLC Harmony Solar ND, LLC Harrington Solar, LLC Hartley Solar, LLC Hearth Solar, LLC Hill River Solar, LLC Honeybee Solar, LLC Hoosier Solar, LLC Hoskins Solar, LLC Illumination Solar, LLC Innovation Solar, LLC Itasca Energy Development, LLC 5 Itasca Energy Services, LLC Jack Rabbit Wind, LLC Jackson County Solar, LLC Junction Solar, LLC KeySpan CI Midstream Limited 3 KeySpan Energy Corporation 8 KeySpan Energy Services Inc. 3 KeySpan Gas East Corporation 8 KeySpan International Corporation 3 KeySpan MHK, Inc. 3 KeySpan Midstream Inc. 3 KeySpan Plumbing Solutions, Inc. 8 Knox Solar, LLC KSI Contracting, LLC 3 KSI Electrical, LLC 3 KSI Mechanical, LLC 3 Lake Charlotte Solar, LLC Lake Iris Solar, LLC Lakeside Solar, LLC Land Management & Development, Inc. 8 Landwest, Inc. 8 Lansing Solar, LLC Leola Wind Farm, LLC Liberty Solar, LLC Lilac Solar, LLC 5 Livingston County Solar, LLC Long Mount Solar, LLC Lordsburg Solar, LLC Louisa Solar, LLC Lowlands Solar, LLC Lydia Solar, LLC Marion County Solar, LLC Massachusetts Electric Company 2 Maverick Wind Farm, LLC Meadowlands Solar, LLC Metrowest Realty LLC 3 Miller Creek Solar, LLC Millers Ferry Solar, LLC Morgan County Solar, LLC Morning Glory Solar, LLC 5 Muddy Creek Solar, LLC Mustang Ridge Wind Farm, LLC Mystic Steamship Corporation 6 Nantucket Electric Company 2 National Grid Development Holdings Corp. 3 National Grid Electric Services LLC 8 National Grid Energy Management LLC 3 National Grid Energy Services LLC 3 National Grid Energy Trading Services LLC 8 National Grid Engineering & Survey Inc. 8 National Grid Generation LLC 8 National Grid Generation Ventures LLC 8 National Grid Glenwood Energy Center, LLC 3 National Grid IGTS Corp. 8 National Grid Insurance USA Ltd 10 National Grid Islander East Pipeline LLC 3 National Grid LNG GP LLC 3 National Grid LNG LLC 3 National Grid LNG LP LLC 3 National Grid Millennium LLC 3 National Grid NE Holdings 2 LLC 2 National Grid North America Inc. 3 National Grid Partners Inc. 8 National Grid Partners LLC 3 National Grid Port Jefferson Energy Center LLC 3 National Grid Renewables Development, LLC National Grid Renewables E Wind, LLC 5 National Grid Renewables Operations, LLC 3 National Grid Renewables Projects, LLC 5 National Grid Renewables Stutsman, LLC National Grid Renewables, LLC 3 National Grid Services Inc. 3 National Grid US 6 LLC 3,† National Grid US LLC 3 National Grid USA Service Company, Inc. 2 National Grid USA 3 NEES Energy, Inc. 2 New England Electric Transmission Corporation 4 New England Energy Incorporated 2 New England Hydro Finance Company, Inc. (53.704%) 2 New England Hydro-Transmission Corporation (53.704%) 4 New England Hydro-Transmission Electric Company, Inc. (53.704%) 2 New England Power Company 2 Newport America Corporation 11 Newton Solar, LLC NG Renewables Energy Marketing, LLC 3 NG Renewables Energy Services, LLC NGNE LLC 3 NGV Emerald Energy Venture Holdings, LLC 3 NGV OSW Holdings, LLC 3 NGV US Distributed Energy Inc. 3 NGV US Transmission Inc. 3 NGV US, LLC 3 Niagara Mohawk Energy, Inc. 3 Niagara Mohawk Holdings, Inc. 8 Niagara Mohawk Power Corporation 8 Niobrara Wind, LLC NM Properties, Inc. 8 Noble Solar, LLC 12 Nordic VOS, LLC North East Transmission Co., Inc. 3 North Fork Wind, LLC Northeast Renewable Link LLC 3 Opinac North America, Inc. 3 Parklawn Solar, LLC Pennington Solar, LLC Peony Solar, LLC Philadelphia Coke Co., Inc. 3 Pierce County Solar, LLC Pike County Solar, LLC Pipestone Solar, LLC Plum Creek Wind Farm 2, LLC Plum Creek Wind Farm, LLC Port of the Islands North, LLC 8 Portage Solar, LLC Prairie Oasis Solar, LLC Prairie Rose Wind 2, LLC 5 Prosperity Wind Farm 2, LLC Prosperity Wind Farm, LLC Red Rock Solar SD, LLC Red Wolf Solar, LLC Regal Solar 2, LLC Regal Solar, LLC River North Solar, LLC Robertson Solar, LLC Rock Ridge Wind Farm, LLC Rolling Hills Solar, LLC Ross County Solar, LLC 6 Royal Solar 2, LLC Royal Solar, LLC Royerton Solar, LLC Saginaw Bay Solar, LLC Sandstone Creek Solar 2, LLC Sandstone Creek Solar, LLC Sapphire Sky Wind Farm, LLC Sherco Solar 2, LLC 5 Sherco Solar, LLC 5 Silver City Solar, LLC Simpson Solar, LLC Spotlight Solar, LLC Spring Brook Solar, LLC Spring River Solar, LLC Springfield Solar Farm, LLC Stony Brook Wind, LLC Stony Point Solar, LLC Stove Creek Solar, LLC Sturgis Solar, LLC Summit Lake Solar, LLC Sunbeam Solar, LLC Sunrise Solar, LLC Sycamore Creek Solar, LLC Thacker Solar, LLC The Brooklyn Union Gas Company 8 The Narragansett Electric Company 11 Torchlight Solar, LLC 5 Transgas Inc. 2 Tri-City Solar, LLC Uintah Solar, LLC Unbridled Solar, LLC Upper Hudson Development Inc. 8 Valley Solar, LLC Vermont Green Line Devco, LLC (90%) 3 Vibrant Solar, LLC Virgo Community Solar Gardens, LLC 5 Virtue Solar, LLC Vivid Solar, LLC Wallowa Solar, LLC Wayfinder Group, Inc. 2 Wheatfield Solar, LLC White Elm Wind Farm, LLC Wild Springs Solar, LLC 5 Wildcat Ridge Wind Farm, LLC Wildhorse Creek Solar, LLC Willard Solar, LLC Williams County Solar, LLC Wiregrass Solar, LLC Woodlands Solar, LLC Worthington Solar, LLC Yellowhammer Solar, LLC Young County Solar, LLC Incorporated in Australia Registered office: Level 7, 330 Collins Street, Melbourne, VIC 3000, Australia National Grid Australia Pty Limited Incorporated in Canada Registered office: Stewart McKelvey LLP, c/o Charles Reagh, Queen’s Marque, 600-1741 Lower Water Street, Halifax, Nova Scotia, B3J 0J2, Canada KeySpan Energy Development Co. Incorporated in Guernsey Registered office: 1st & 2nd Floors Elizabeth House, Les Ruettes Brayes, St Peter Port, GY1 1EW, Guernsey, Channel Islands WPD Limited (Guernsey) † Registered office: PO Box 155, Mill Court, La Charroterie, St. Peter Port, Guernsey, GY1 4ET, Guernsey, Channel Islands Aztec Insurance Limited Incorporated in Hong Kong Registered office: Level 54, Hopewell Centre, 183 Queen’s Road East, Hong Kong National Grid Hong Kong Limited † Incorporated in the Isle of Man Registered office: Third Floor, St George’s Court, Upper Church Street, Douglas, IM1 1EE, Isle of Man, UK National Grid Insurance Company (Isle of Man) Limited NGT Holding Company (Isle of Man) Limited* † Incorporated in Luxembourg Registered office: 412F, Route d’Esch, L-2086, Luxembourg, Grand Duchy of Luxembourg National Grid Luxembourg SARL Incorporated in the Netherlands Registered office: Westblaak 89, 3012 KG Rotterdam, PO Box 21153, 3001 AD, Rotterdam, Netherlands British Transco International Finance B.V. Incorporated in the Republic of Ireland Registered office: c/o Moore Stephens Nathans, Third Floor, Ulysses House, 23/24 Foley Street, Dublin, D01 W2T2, Ireland National Grid Company (Ireland) Designated Activity Company* 1. Registered office: National Registered Agents, Inc., 160 Greentree Drive, Suite 101, Dover DE 19904, USA. 2. Registered office: Corporation Service Company, 84 State Street, Boston MA 02109, USA. 3. Registered office: Corporation Service Company, 251 Little Falls Drive, Wilmington DE 19808, USA. 4. Registered office: Corporation Service Company, 10 Ferry Street, Suite 313, Concord NH 03301, USA. 5. Registered office: National Grid Renewables Development, LLC, 8400 Normandale Lake Blvd. Suite 1200, Bloomington, MN 55437, USA. 6. Registered office: The Corporation Trust Company, Corporation Trust Center, 1209 Orange Street, Wilmington, Delaware, 19801, USA. 7. Registered office: 60 Mine Lake Court, Suite 200, Raleigh, Wake County, NC 27615, USA. 8. Registered office: Corporation Service Company, 80 State Street, Albany NY 12207, USA. 9. Registered office: National Registered Agents, Inc., 30600 Telegraph Road, Suite 2345, Bingham Farms, MI 48025-5720, USA. 10. Registered office: One MetroTech Center, Brooklyn NY 11201, USA. 11. Registered office: Corporation Service Company, 222 Jefferson Boulevard, Suite 200, Warwick RI 02888, USA. 12. Registered office: National Registered Agents, Inc., 1999 Bryan Street, Dallas, Dallas County TX 75201, USA. * In liquidation. † Entity is tax resident in the United Kingdom. A list of the Group’s joint ventures as at 31 March 2022 is given below. All joint ventures are included in the Group’s financial statements using the equity method of accounting. Principal joint ventures are identified in bold . Incorporated in England and Wales Registered office: 1–3 Strand, London WC2N 5EH, UK (unless stated otherwise in footnotes). BritNed Development Limited (50%)* Joint Radio Company Limited (50%) 1 ** National Places LLP (50%) 2 Nemo Link Limited (50%) NGET/SPT Upgrades Limited (50%) † Incorporated in the US Registered office: Corporation Service Company, 251 Little Falls Drive, Wilmington, DE 19808, USA (unless stated otherwise in footnotes). Bight Wind Holdings, LLC (27.27%) 3 Clean Energy Storage Systems LLC (previously Clean Energy Generation, LLC) (50%) Emerald Energy Venture LLC (51%) Island Park Energy Center, LLC (50%) Islander East Pipeline Company, LLC (50%) 3 LI Energy Storage System, LLC (50%) LI Solar Generation, LLC (50%) Incorporated in France Registered office: 1 Terrasse Bellini, Tour Initiale, TSA 41000 – 9291, IFA2 (50%) A list of the Group’s associates as at 31 March 2022 is given below. Unless otherwise stated, all associates are included in the Group’s financial statements using the equity method of accounting. Principal associates are identified in bold . Incorporated in the US Registered office: Corporation Service Company, 251 Little Falls Drive, Wilmington, DE 19808, USA (unless stated otherwise in footnotes). Clean Line Energy Partners LLC (32%) 3 Connecticut Yankee Atomic Power Company (19.5%) 4 Direct Global Power, Inc. (26%) 3 Energy Impact Fund LP (9.41%) 5 KHB Venture LLC (33.33%) 6 Maine Yankee Atomic Power Company (24%) 7 Millennium Pipeline Company, LLC (26.25%) 3 New York Transco LLC (28.3%) 8 NYSEARCH RMLD, LLC (22.63%) The Hive IV, LLC (28.2%) 3 Yankee Atomic Electric Company (34.5%) 9 Incorporated in Belgium Registered office: Avenue de Cortenbergh 71, 1000 Brussels, Belgium Coreso SA (15.84%) Other investments A list of the Group’s other investments as at 31 March 2022 is given below. Incorporated in England and Wales Registered office: 1 More London Place, London SE1 2AF, UK Energis plc (33.06%)‡ Registered office: Third Floor, Northumberland House, 303–306 High Holborn, London, WC1V 7JZ Electralink Limited (27.04%) 1. Registered office: Friars House, Manor House Drive, Coventry, CV1 2TE, UK. 2. Registered office: 80 Cheapside, London, EC2V 6EE, UK. 3. Registered office: The Corporation Trust Company, Corporation Trust Center, 1209 Orange Street, Wilmington DE 19801, USA. 4. Registered office: Carla Pizzella, 362 Injun Hollow Road, East Hampton CT 06424-3099, USA. 5. Registered office: Harvard Business Services, Inc., 16192 Coastal Highway, Lewes DE 19958, USA. 6. Registered office: De Maximus Inc., 135 Beaver Street, 4th Floor, Waltham MA 02452, USA. 7. Registered office: Joseph D Fay, 321 Old Ferry Road, Wiscasset ME 04578, USA. 8. Registered office: Corporation Service Company, 80 State Street, Albany NY 12207, USA. 9. Registered office: Karen Sucharzewski, 49 Yankee Road, Rowe MA 01367, USA. * National Grid Interconnector Holdings Limited owns 284,500,000 €0.20 C Ordinary shares and one £1.00 Ordinary A share. ** National Grid Gas plc owns all £1.00 A Ordinary shares. † National Grid Electricity Transmission plc owns 50 £1.00 A Ordinary shares. ‡ In administration. Our interests and activities are held or operated through the subsidiaries, joint arrangements or associates as disclosed above. These interests and activities (and their branches) are established in – and subject to the laws and regulations of – these jurisdictions. The following UK subsidiaries will take advantage of the audit exemption set out within section 479A of the Companies Act 2006 supported by guarantees issued by National Grid plc over their liabilities for the year ended 31 March 2022: Company name Company number NatGrid One Limited 5521240 Natgrid TW1 Limited 7579324 National Grid Holdings Limited 3096772 National Grid International Limited 2537092 National Grid Twelve Limited 4355616 National Grid Twenty Three Limited 6999009 National Grid (US) Holdings Limited 2630496 National Grid (US) Investments 2 Limited 3784528 National Grid (US) Investments 4 Limited 3867128 National Grid (US) Partner 1 Limited 4314432

Sensitivites

Sensitivites	12 Months Ended
	Mar. 31, 2022
Disclosure of sensitivity analysis for actuarial assumptions [abstract]
Sensitivities	32. Financial risk management Our activities expose us to a variety of financial risks including credit risk, liquidity risk, capital risk, currency risk, interest rate risk, inflation risk and commodity price risk. Our risk management programme focuses on the unpredictability of financial markets and seeks to minimise potential volatility of financial performance from these risks. We use financial instruments, including derivative financial instruments, to manage these risks. Risk management related to financing activities is carried out by a central treasury department under policies approved by the Finance Committee of the Board. The objective of the treasury department is to manage funding and liquidity requirements, including managing associated financial risks, to within acceptable boundaries. The Finance Committee provides written principles for overall risk management, and written policies covering the following specific areas: foreign exchange risk, interest rate risk, credit risk, liquidity risk, use of derivative financial instruments and non-derivative financial instruments, and investment of excess liquidity. The Finance Committee has delegated authority to administer the commodity price risk policy and credit policy for US‑based commodity transactions to the Energy Procurement Risk Management Committee and the National Grid USA Board of Directors. We have exposure to the following risks, which are described in more detail below: • credit risk; • liquidity risk; • currency risk; • interest rate risk; • commodity price risk; and • capital risk. Where appropriate, derivatives and other financial instruments used for hedging currency and interest rate risk exposures are formally designated as fair value, cash flow or net investment hedges as defined in IFRS 9. Hedge accounting allows the timing of the profit or loss impact of qualifying hedging instruments to be recognised in the same reporting period as the corresponding impact of hedged exposures. To qualify for hedge accounting, documentation is prepared specifying the risk management objective and strategy, the component transactions and methodology used for measurement of effectiveness. 32. Financial risk management continued Hedge accounting relationships are designated in line with risk management activities further described below. The categories of hedging entered into are as follows: • currency risk arising from our forecasted foreign currency transactions (capital expenditure or revenues) is designated in cash flow hedges; • currency risk arising from our net investments in foreign operations is designated in net investment hedges; and • currency and interest rate risk arising from borrowings are designated in cash flow or fair value hedges. Critical terms of hedging instruments and hedged items are transacted to match on a 1:1 ratio by notional values. Hedge ineffectiveness can nonetheless arise from inherent differences between derivatives and non-derivative instruments and other market factors including credit, correlations, supply and demand, and market volatilities. Ineffectiveness is recognised in the remeasurements component of finance income and costs (see note 6). Hedge accounting is discontinued when a hedging relationship no longer qualifies for hedge accounting. Certain hedging instrument components are treated separately as costs of hedging with the gains and losses deferred in a component of other equity reserves and released systematically into profit or loss to correspond with the timing and impact of hedged exposures, or released in full to finance costs upon an early discontinuation of a hedging relationship. Refer to sections (c) currency risk and (d) interest rate risk below for further details on hedge accounting. (a) Credit risk We are exposed to the risk of loss resulting from counterparties’ default on their commitments including failure to pay or make a delivery on a contract. This risk is inherent in our commercial business activities. Exposure arises from derivative financial instruments, deposits with banks and financial institutions, trade receivables and committed transactions with wholesale and retail customers. Treasury credit risk Counterparty risk arises from the investment of surplus funds and from the use of derivative financial instruments. As at 31 March 2022, the following limits were in place for investments and derivative financial instruments held with banks and financial institutions: Maximum limit Long-term limit Triple ‘A’ G7 sovereign entities (AAA) 2,708 2,031 Triple ‘A’ vehicles (AAA) 500 — Triple ‘A’ range institutions and non-G7 sovereign entities (AAA) 2,462 1,847 Double ‘A+’ G7 sovereign entities (AA+) 2,462 1,847 Double ‘A’ range institutions (AA) 1,477 to 1,970 1,108 to 1,477 Single ‘A’ range institutions (A) 492 to 985 369 to 739 The maximum limit applies to all transactions, including long-term transactions. The long-term limit applies to transactions which mature in more than 12 months’ time. As at 31 March 2022 and 2021, we had a number of exposures to individual counterparties. In accordance with our treasury policies, counterparty credit exposure utilisations are monitored daily against the counterparty credit limits. Counterparty credit ratings and market conditions are reviewed continually with limits being revised and utilisation adjusted, if appropriate. Management does not expect any significant losses from non-performance by these counterparties. Further information on financial investments subject to impairment provisioning is included in note 15. Commodity credit risk The credit policy for US-based commodity transactions is owned by the Finance Committee to the Board, which establishes controls and procedures to determine, monitor and minimise the credit exposure to counterparties. Wholesale and retail credit risk Our principal commercial exposure in the UK is governed by the credit rules within the regulated codes: Uniform Network Code and Connection and Use of System Code. These set out the level of credit relative to the RAV for each credit rating. In the US, we are required to supply electricity and gas under state regulations. Our policies and practices are designed to limit credit exposure by collecting security deposits prior to providing utility services, or after utility services have commenced if certain applicable regulatory requirements are met. Collection activities are managed on a daily basis. Sales to retail customers are usually settled in cash, cheques, electronic bank payments or by using major credit cards. We are committed to measuring, monitoring, minimising and recording counterparty credit risk in our wholesale business. The utilisation of credit limits is regularly monitored, and collateral is collected against these accounts when necessary. In March 2020, the Group’s US distribution business temporarily ceased certain cash collection and termination activities in response to regulatory instructions following the COVID-19 pandemic. At the time this resulted in the recognition of expected credit losses. In the year ended 31 March 2022, collection activities resumed in New England and New York and are supported by certain government COVID funding programmes, which has been factored into the assessment of expected credit losses for the year (see note 19 for further details). 32. Financial risk management continued (a) Credit risk continued Offsetting financial assets and liabilities The following tables set out our financial assets and liabilities which are subject to offset and to enforceable master netting arrangements or similar agreements. The tables show the amounts which are offset and reported net in the statement of financial position. Amounts which cannot be offset under IFRS, but which could be settled net under terms of master netting arrangements if certain conditions arise, and with collateral received or pledged, are shown to present National Grid’s net exposure. Financial assets and liabilities on different transactions would only be reported net in the balance sheet if the transactions were with the same counterparty, a currently enforceable legal right of offset exists, and the cash flows were intended to be settled on a net basis. Amounts which do not meet the criteria for offsetting on the statement of financial position, but could be settled net in certain circumstances, principally relate to derivative transactions under ISDA agreements, where each party has the option to settle amounts on a net basis in the event of default of the other party. Commodity contract derivatives that have not been offset on the balance sheet may be settled net in certain circumstances under ISDA or North American Energy Standards Board (NAESB) agreements. For bank account balances and bank overdrafts, there are no ‘Gross amounts offset’ under cash pooling arrangements (2021: £nil). Our UK bank accounts for National Grid subsidiaries previously participated in GBP, EUR and USD Composite Accounting System overdraft facilities subject to offsetting gross and net overdraft limits. EUR and USD offsetting arrangements were discontinued in the prior year and GBP offsetting arrangements have no impact as at 31 March 2022. In the US, no offsetting arrangements exist, and cash transactions are settled through Service Company bank accounts with subsequent intercompany payables and receivables reported by subsidiaries with the Service Company. The gross amounts offset for trade payables and receivables, which are subject to general terms and conditions, are insignificant. Related amounts At 31 March 2022 Gross Gross Net amount Financial instruments Cash Net amount Assets Financing derivatives 298 — 298 (136) (55) 107 Commodity contract derivatives 289 — 289 (8) (50) 231 587 — 587 (144) (105) 338 Liabilities Financing derivatives (991) — (991) 136 771 (84) Commodity contract derivatives (22) — (22) 8 3 (11) (1,013) — (1,013) 144 774 (95) (426) — (426) — 669 243 Related amounts At 31 March 2021 Gross carrying amounts £m Gross Net amount presented in statement of financial position £m Financial instruments £m Cash collateral received/ pledged £m Net amount £m Assets Financing derivatives 942 — 942 (234) (561) 147 Commodity contract derivatives 57 — 57 (8) — 49 999 — 999 (242) (561) 196 Liabilities Financing derivatives (767) — (767) 234 467 (66) Commodity contract derivatives (132) — (132) 8 4 (120) (899) — (899) 242 471 (186) 100 — 100 — (90) 10 32. Financial risk management continued (b) Liquidity risk Our policy is to determine our liquidity requirements by the use of both short-term and long-term cash flow forecasts. These forecasts are supplemented by a financial headroom analysis which is used to assess funding requirements for at least a 24-month period and maintain adequate liquidity for a continuous 12-month period. We believe our contractual obligations, including those shown in commitments and contingencies in note 30, can be met from existing cash and investments, operating cash flows and other financing that we reasonably expect to be able to secure in the future, together with the use of committed facilities if required. Our debt agreements and banking facilities contain covenants, including those relating to the periodic and timely provision of financial information by the issuing entity, restrictions on disposals and financial covenants, such as restrictions on the level of subsidiary indebtedness and interest coverage. Failure to comply with these covenants, or to obtain waivers of those requirements, could in some cases trigger a right, at the lender’s discretion, to require repayment of some of our debt and may restrict our ability to draw upon our facilities or access the capital markets. The following is a payment profile of our financial liabilities and derivatives: At 31 March 2022 Less than £m 1 to 2 2 to 3 More than Total Non-derivative financial liabilities Borrowings, excluding lease liabilities (11,589) (1,322) (2,468) (28,119) (43,498) Interest payments on borrowings¹ (970) (928) (883) (12,525) (15,306) Lease liabilities (132) (96) (79) (366) (673) Other non-interest-bearing liabilities (3,979) (336) — — (4,315) Contingent consideration (37) (8) — — (45) Derivative financial liabilities Financing derivatives – receipts² 3,149 1,008 2,075 4,726 10,958 Financing derivatives – payments² (3,401) (1,189) (2,336) (5,468) (12,394) Commodity contract derivatives – receipts² 1 1 — — 2 Commodity contract derivatives – payments² (29) 2 (1) — (28) Derivative financial assets Financing derivatives – receipts² 4,512 316 1,427 464 6,719 Financing derivatives – payments² (4,405) (282) (1,313) (405) (6,405) Commodity contract derivatives – receipts² 234 37 3 — 274 Commodity contract derivatives – payments² (52) (8) (3) — (63) (16,698) (2,805) (3,578) (41,693) (64,774) At 31 March 2021 Less than 1 year £m 1 to 2 2 to 3 years £m More than 3 years £m Total £m Non-derivative financial liabilities Borrowings, excluding lease liabilities (3,350) (1,690) (806) (25,562) (31,408) Interest payments on borrowings¹ (810) (755) (731) (12,018) (14,314) Lease liabilities (118) (108) (90) (599) (915) Other non-interest-bearing liabilities (3,207) (350) — — (3,557) Contingent consideration (40) (24) — — (64) Derivative financial liabilities Financing derivatives – receipts² 3,773 749 451 4,326 9,299 Financing derivatives – payments² (3,899) (877) (533) (5,153) (10,462) Commodity contract derivatives – receipts² 12 — — — 12 Commodity contract derivatives – payments² (83) (23) (14) (12) (132) Derivative financial assets Financing derivatives – receipts² 2,162 926 833 1,789 5,710 Financing derivatives – payments² (1,700) (834) (780) (1,536) (4,850) Commodity contract derivatives – receipts² 21 4 1 1 27 Commodity contract derivatives – payments² (21) (4) (2) — (27) (7,260) (2,986) (1,671) (38,764) (50,681) 1. The interest on borrowings is calculated based on borrowings held at 31 March without taking account of future issues. Floating rate interest is estimated using a forward interest rate curve as at 31 March. Payments are included on the basis of the earliest date on which the Company can be required to settle. 2. The receipts and payments line items for derivatives comprise gross undiscounted future cash flows, after considering any contractual netting that applies within individual contracts. Where cash receipts and payments within a derivative contract are settled net, and the amount to be received/(paid) exceeds the amount to be paid/(received), the net amount is presented within derivative receipts/(payments). 32. Financial risk management continued (c) Currency risk National Grid operates internationally with mainly pound sterling as the functional currency for the UK companies and US dollar for the US businesses. Currency risk arises from three major areas: funding activities, capital investment and related revenues, and holdings in foreign operations. This risk is managed using financial instruments including derivatives as approved by policy, typically cross-currency interest rate swaps, foreign exchange swaps and forwards. Funding activities – our policy is to borrow in the most advantageous market available. Foreign currency funding gives rise to risk of volatility in the amount of functional currency cash to be repaid. This risk is reduced by swapping principal and interest back into the functional currency of the issuer. All foreign currency debt and transactions are hedged except where they provide a natural offset to assets elsewhere in the Group. Capital investment and related revenues – capital projects often incur costs or generate revenues in a foreign currency, most often euro transactions done by the UK business. Our policy for managing foreign exchange transaction risk is to hedge contractually committed foreign currency cash flows over a prescribed minimum size, typically by buying euro forwards to hedge future expenditure, and selling euro forwards to hedge future revenues. For hedges of forecast cash flows our policy is to hedge a proportion of highly probable cash flows. Holdings in foreign operations – we are exposed to fluctuations on the translation into pounds sterling of our foreign operations. The policy for managing this translation risk is to issue foreign currency debt or to replicate foreign debt using derivatives that pay cash flows in the currency of the foreign operation. The primary managed exposure arises from dollar denominated assets and liabilities held by our US operations, with a smaller euro exposure in respect of joint venture investments. Derivative financial instruments were used to manage foreign currency risk as follows: 2022 2021 Sterling Euro Dollar Other Total Sterling £m Euro £m Dollar £m Other £m Total £m Cash and cash equivalents 111 — 93 — 204 63 — 94 — 157 Financial investments 1,725 — 1,420 — 3,145 1,215 — 1,127 — 2,342 Borrowings (22,910) (7,052) (14,118) (1,385) (45,465) (12,210) (5,351) (12,660) (999) (31,220) Pre-derivative position (21,074) (7,052) (12,605) (1,385) (42,116) (10,932) (5,351) (11,439) (999) (28,721) Derivative effect (1,378) 6,849 (7,570) 1,406 (693) (826) 5,459 (5,494) 1,036 175 Net debt position (22,452) (203) (20,175) 21 (42,809) (11,758) 108 (16,933) 37 (28,546) The exposure to dollars largely relates to our net investment hedge activities and exposure to euros largely relates to hedges for our future non-sterling capital expenditure. The currency exposure on other financial instruments is as follows: 2022 2021 Sterling Euro Dollar Other Total Sterling £m Euro £m Dollar £m Other £m Total £m Trade and other receivables 407 — 1,788 — 2,195 282 — 1,387 — 1,669 Trade and other payables (1,459) — (2,554) — (4,013) (1,207) — (1,878) — (3,085) Other non-current liabilities (90) — (253) — (343) (77) — (288) — (365) The carrying amounts of other financial instruments are denominated in the above currencies, which in most instances are the functional currency of the respective subsidiaries. Our exposure to dollars is due to activities in our US subsidiaries. We do not have any other significant exposure to currency risk on these balances. Hedge accounting for currency risk Where available, derivatives transacted for hedging are designated for hedge accounting. Economic offset is qualitatively determined because the critical terms (currency and volume) of the hedging instrument match the hedged exposure. If a forecast transaction was no longer expected to occur, the cumulative gain or loss previously reported in equity would be transferred to the income statement. This has not occurred in the current or comparative years. Cash flow hedging of currency risk of capital expenditure and revenues is designated as hedging the exposure to movements in the spot translation rates only. The timing of forecasted transactions is not designated as a hedged risk. Gains and losses on hedging instruments arising from forward points and foreign currency basis spreads are excluded from designation and are recognised immediately in profit or loss, along with any hedge ineffectiveness. On recognition of the hedged purchase or sale in the financial statements, the associated hedge gains and losses, deferred in the cash flow hedge reserve in other equity reserves, are transferred out of reserves and included with the recognition of the underlying transaction. Where a non-financial asset or a non-financial liability results from a forecast transaction or firm commitment being hedged, the amounts deferred in reserves are included directly in the initial measurement of that asset or liability. Net investment hedging is also designated as hedging the exposure to movements in spot translation rates only: spot-related gains and losses on hedging instruments are presented in the cumulative translation reserve within other equity reserves to offset gains or losses on translation of the hedged balance sheet exposure. Any ineffectiveness is recognised immediately in the income statement. Amounts deferred in the cumulative translation reserve with respect to net investment hedges are subsequently recognised in the income statement in the event of disposal of the overseas operations concerned. Any remaining amounts deferred in the cost of hedging reserve are also released to the income statement. Hedges of foreign currency funding are designated as cash flow hedges or fair value hedges of forward exchange risk (hedging both currency and interest rate risk together, where applicable). Gains and losses arising from foreign currency basis spreads are excluded from designation and are treated as a cost of hedging, deferred initially in other equity reserves and released into profit or loss over the life of the hedging relationship. Hedge accounting for funding is described further in the interest rate risk section below. 32. Financial risk management continued (d) Interest rate risk National Grid’s interest rate risk arises from our long-term borrowings. Our interest rate risk management policy is to seek to minimise total financing costs (being interest costs and changes in the market value of debt). Hedging instruments principally consist of interest rate and cross-currency swaps that are used to translate foreign currency debt into functional currency and to adjust the proportion of fixed-rate and floating-rate in the borrowings portfolio to within a range set by the Finance Committee of the Board. The benchmark interest rates hedged are currently based on LIBOR for USD and Sterling Overnight Index Average (SONIA) for GBP. LIBOR is being replaced as an interest rate benchmark by alternative reference rates in certain currencies including our functional currencies, USD and GBP, and foreign currencies in which we operate. This impacts contracts including financial liabilities that pay LIBOR-based cash flows, and derivatives that receive or pay LIBOR-based cash flows. The change in benchmark also affects discount rates which will impact the valuations of certain liabilities. We have disclosed our exposure to LIBOR on our derivative portfolio in note 17, on our borrowings in note 21 and on our hedging arrangements in note 32(e). We are managing the risk by transitioning LIBOR cash flows to alternative reference rates on our affected contracts in line with the relevant jurisdictions. The migration project is underway, with all affected contracts where we previously paid or received GBP LIBOR amended in the year to 31 March 2022 (see note 21). The Finance Committee of the Board have delegated to the treasury department the authority to determine which benchmarks are the most appropriate. A combination of LIBOR and the successor benchmarks, primarily GBP SONIA and USD Secured Overnight Financing Rate (SOFR) will be used in the portfolio during the migration period. We also consider inflation risk and hold some inflation-linked borrowings. We believe that these provide a partial economic offset to the inflation risk associated with our UK inflation-linked revenues. The table in note 21 sets out the carrying amount, by contractual maturity, of borrowings that are exposed to interest rate risk before taking into account interest rate swaps. Net debt was managed using derivative financial instruments to hedge interest rate risk as follows: 2022 2021 Fixed rate £m Floating rate £m Inflation linked £m Other 1 £m Total £m Fixed rate £m Floating rate £m Inflation linked £m Other 1 £m Total £m Cash and cash equivalents 82 118 — 4 204 64 67 — 26 157 Financial investments — 3,107 — 38 3,145 — 2,309 — 33 2,342 Borrowings (30,616) (10,484) (4,365) — (45,465) (23,163) (1,762) (6,295) — (31,220) Pre-derivative position (30,534) (7,259) (4,365) 42 (42,116) (23,099) 614 (6,295) 59 (28,721) Derivative effect 2,860 (3,366) (187) — (693) 2,869 (2,511) (183) — 175 Net debt position (27,674) (10,625) (4,552) 42 (42,809) (20,230) (1,897) (6,478) 59 (28,546) 1. Represents financial instruments which are not directly affected by interest rate risk, such as investments in equity or other similar financial instruments. Hedge accounting for interest rate risk Borrowings paying variable or floating-rates expose National Grid to cash flow interest rate risk, partially offset by cash held at variable rates. Where a hedging instrument results in paying a fixed-rate, it is designated as a cash flow hedge because it has reduced the cash flow volatility of the hedged borrowing. Changes in the fair value of the derivative are initially recognised in other comprehensive income as gains or losses in the cash flow hedge reserve, with any ineffective portion recognised immediately in the income statement. Borrowings paying fixed-rates expose National Grid to fair value interest rate risk. Where the hedging instrument pays a floating-rate, it is designated as a fair value hedge because it has reduced the fair value volatility of the borrowing. Changes in the fair value of the derivative and changes in the fair value of the hedged item in relation to the risk being hedged are both adjusted on the balance sheet and offset in the income statement to the extent the fair value hedge is effective, with the residual difference remaining as ineffectiveness. Both types of hedges are designated as hedging the currency and interest rate risk arising from changes in forward points. Amounts accumulated in the cash flow hedge reserve (cash flow hedges only) and the deferred cost of hedging reserve (both cash flow and fair value hedges) are reclassified from reserves to the income statement on a systematic basis as hedged interest expense is recognised. Adjustments made to the carrying value of hedged items in fair value hedges are similarly released to the income statement to match the timing of the hedged interest expense. When hedge accounting is discontinued, any remaining cumulative hedge accounting balances continue to be released to the income statement to match the impact of outstanding hedged items. Any remaining amounts deferred in the cost of hedging reserve are released immediately to the income statement as finance costs. The Group early-adopted Phase I of IFRS Interest Rate Benchmark Reform amendments related to hedge accounting with effect from 1 April 2019, and Phase II with effect from 1 April 2020. The amendments impact our fair value hedging relationships where derivative cash flows will have been transitioned from paying LIBOR to paying an alternative reference rate. The hedged risk must be re-documented to reflect this, and allow existing hedge designations to continue unchanged during the period of uncertainty relating to the timing and method of benchmark migrations. This process has been completed for sterling LIBOR contracts but remains in progress for US dollar contracts. The amendments will be applied until the earliest point in time of the Group’s contracts that reference LIBOR being amended, the hedging relationship being formally discontinued or formal market conventions ending uncertainty being published and widely adopted. If amended cash flows do not cause a hedging relationship to be discontinued, then the amendments will cease to be applied only when that relationship is discontinued under IFRS 9. The IFRS amendments impact fair value and cash flow hedges of interest rate risk and related hedging instruments, and certain net investment hedges that use cross-currency interest rate swaps to pay a foreign currency floating rate and receive a functional currency floating rate. The notional values of hedging instruments, for each type of hedging relationship impacted, are shown in the hedge accounting tables in note 32(e). These amounts also correspond to the exposures designated as hedged. 32. Financial risk management continued (e) Hedge accounting In accordance with the requirements of IFRS 7, certain additional information about hedge accounting is disaggregated by risk type and hedge designation type in the tables below: Year ended 31 March 2022 Fair value hedges of foreign currency and interest rate risk Cash flow hedges of foreign currency and interest rate risk Cash flow hedges of foreign currency risk Net investment hedges Consolidated statement of comprehensive income Net gains/(losses) in respect of: Cash flow hedges — (103) (1) — Cost of hedging (7) 16 — (7) Transferred to profit or loss in respect of: Cash flow hedges — 43 — — Cost of hedging 1 — — (2) Consolidated statement of changes in equity Other equity reserves – cost of hedging balances (15) (16) — (3) Consolidated statement of financial position Derivatives – carrying value of hedging instruments ¹ Assets – current — — 1 10 Assets – non-current 49 67 1 82 Liabilities – current (21) (22) (37) (16) Liabilities – non-current (310) (303) (8) — Profiles of the significant timing, price and rate information of hedging instruments Maturity range Jul 2022 – Sep 2044 Jun 2022 – Nov 2040 Apr 2022 – Feb 2027 Sep 2022 – Sep 2027 Spot foreign exchange range: GBP:USD n/a 1.30 – 1.66 1.34 – 1.41 1.22 – 1.34 GBP:EUR 1.11 – 1.24 1.08 – 1.24 1.04 – 1.19 1.18 EUR:USD 1.13 – 1.17 1.13 – 1.15 n/a n/a Interest rate range: GBP SONIA +84bps/+374bps 0.976% – 7.410% n/a n/a USD LIBOR +68bps/+115bps 2.095% – 3.864% n/a n/a 1. The use of derivatives may entail a derivative transaction qualifying for more than one hedge type designation under IFRS 9. Therefore, the derivative amounts in the table above are grossed up by hedge type, whereas they are presented net at an instrument level in the statement of financial position. 32. Financial risk management continued (e) Hedge accounting continued Year ended 31 March 2021 Fair value hedges of foreign currency and interest rate risk Cash flow hedges of Cash flow hedges of Net investment hedges Consolidated statement of comprehensive income Net losses in respect of: Cash flow hedges — 14 (14) — Cost of hedging (15) (24) — 50 Transferred to profit or loss in respect of: Cash flow hedges — 56 — — Cost of hedging 1 2 — — Consolidated statement of changes in equity Other equity reserves – cost of hedging balances (11) (30) — 6 Consolidated statement of financial position Derivatives – carrying value of hedging instruments¹ Assets – current — 10 2 5 Assets – non-current 187 59 1 140 Liabilities – current — (12) (24) (17) Liabilities – non-current (113) (255) (22) — Profiles of the significant timing, price and rate information of hedging instruments Maturity range Jan 2023 – Jan 2043 Sep 2021 – Nov 2040 Apr 2021 – Feb 2027 Mar 2022 – Sep 2027 Spot foreign exchange range: GBP:USD 1.64 1.30 – 1.66 1.31 – 1.41 1.22 – 1.40 GBP:EUR 1.11 – 1.24 1.08 – 1.24 1.04 – 1.29 1.15 – 1.16 EUR:USD 1.13 – 1.17 1.13 – 1.14 n/a n/a Interest rate range: GBP LIBOR +30bps/+408bps 0.976% – 5.845% n/a n/a USD LIBOR –68bps/+115bps 2.513% – 3.864% n/a n/a 1. The use of derivatives may entail a derivative transaction qualifying for more than one hedge type designation under IFRS 9. Therefore, the derivative amounts in the table above are grossed up by hedge type, whereas they are presented net at an instrument level in the statement of financial position. 32. Financial risk management continued (e) Hedge accounting continued The following tables show the effects of hedge accounting on financial position and year-to-date performance for each type of hedge. These tables also present notional values of hedging instruments (and equal hedged exposures) impacted by IFRS 9 Interest Rate Benchmark Reform amendments. (i) Fair value hedges of foreign currency and interest rate risk on recognised borrowings: As at 31 March 2022 Balance of fair value hedge adjustments in borrowings Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings 1,2 (3,362) 437 (55) 340 (301) 39 1. The carrying value of the hedged borrowings is £2,966 million, of which £nil is current and £2,966 million is non-current. 2. Included within the hedging instrument notional balance is £2,556 million impacted by Interest Rate Benchmark Reform amendments with £806 million still to be transitioned. As at 31 March 2021 Balance of fair value hedge adjustments in borrowings Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings 1,2 (2,755) 121 (85) 153 (127) 26 1. The carrying value of the hedged borrowings was £2,714 million, of which £nil was current and £2,714 million was non-current.

Additional disclosures in respe

Additional disclosures in respect of guaranteed securities	12 Months Ended
	Mar. 31, 2022
Separate Financial Statements [Abstract]
Additional disclosures in respect of guaranteed securities	36. Additional disclosures in respect of guaranteed securities Niagara Mohawk Power Corporation, a wholly owned subsidiary of the Group, has issued preferred shares that are listed on a US national securities exchange and are guaranteed by National Grid plc. This guarantor commits to honour any liabilities should the company issuing the debt have any financial difficulties. In order to provide debt holders with information on the financial stability of the company providing the guarantee, we are required to disclose individual financial information for this company. We have chosen to include this information in the Group financial statements rather than submitting separate stand-alone financial statements. The following summarised financial information is given in respect of Niagara Mohawk Power Corporation as a result of National Grid plc’s guarantee, dated 29 October 2007, of Niagara Mohawk Power Corporation’s 3.6% and 3.9% issued preferred shares, which amount to £29 million. National Grid plc’s guarantee of Niagara Mohawk Power Corporation’s preferred shares is full and unconditional. There are no restrictions on the payment of dividends by Niagara Mohawk Power Corporation or limitations on National Grid plc’s guarantee of the preferred shares, and there are no factors that may affect payments to holders of the guaranteed securities. The following summarised financial information for National Grid plc and Niagara Mohawk Power Corporation is presented on a combined basis and is intended to provide investors with meaningful and comparable financial information, and is provided pursuant to the early adoption of Rule 13-01 of Regulation S-X in lieu of the separate financial statements of Niagara Mohawk Power Corporation. Summarised financial information is presented, on a combined basis, as at 31 March 2022. The combined amounts are presented under IFRS measurement principles. Intercompany transactions have been eliminated. Investments in other non-issuer and non-guarantor subsidiaries are included at cost, subject to impairment. Summarised financial information for the year ended 31 March 2022 – IFRS National Grid plc and Niagara Mohawk Power Corporation combined £m Combined statement of financial position Non-current loans to other subsidiaries — Non-current assets 10,068 Current loans to other subsidiaries 28,525 Current assets 2,431 Current loans from other subsidiaries (14,512) Current liabilities (10,276) Non-current loans from other subsidiaries (2,050) Non-current liabilities (8,294) Net assets ¹ 5,892 Equity 5,892 Combined income statement – continuing operations Revenue 2,987 Operating costs (2,358) Operating profit 629 Other income from other subsidiaries 2,500 Other income and costs, including taxation (360) Profit after tax 2,769 1. Excluded from net assets above are investments in other consolidated subsidiaries with a carrying value of £14,440 million.

Acquisitions

Acquisitions	12 Months Ended
	Mar. 31, 2022
Business Combinations [Abstract]
Acquisitions	37. Acquisitions Business combinations are accounted for using the acquisition method. The identifiable assets acquired and liabilities assumed are recognised at their fair values at the acquisition date. Goodwill is initially measured as the excess of the aggregate of the consideration transferred, the amount recognised for any non-controlling interest and the acquisition-date fair values of any previously held interest in the acquiree over the fair value of the identifiable assets acquired and liabilities assumed at the acquisition date. Acquisition-related costs are expensed as incurred and included within Other operating income and costs. Acquisition of WPD On 14 June 2021, National Grid plc acquired 100% of the share capital of PPL WPD Investments Limited (WPD), the holding company of Western Power Distribution plc, which is the UK’s largest electricity distribution network operator. The acquisition, along with the two planned disposals disclosed in note 10, strategically pivots National Grid’s UK portfolio towards electricity, in order to significantly enhance National Grid’s role in the delivery of the UK’s net zero targets, given that electricity distribution is expected to see a high level of asset growth as a result of the ongoing energy transition. The total cash consideration for the transaction was £7.9 billion, all of which was paid upfront, with no further contingent or deferred consideration payable. As a result of the acquisition, one of WPD’s existing borrowing facilities became repayable immediately due to a change in control clause within the original borrowing agreement. The borrowing facility was immediately replaced with an intercompany loan of £350 million from National Grid plc. National Grid funded the transaction price and the new intercompany loan by taking out a bridge financing facility (see note 33), that it will commence repaying with the proceeds of the planned disposals. The fair values of the assets and liabilities following the finalisation of the purchase price allocation are set out below: IFRS book value at acquisition Fair value adjustments Fair value Non-current assets Property, plant and equipment 14,077 (4,026) 10,051 Other intangible assets 49 1,714 1,763 Pension assets 402 164 566 Other non-current assets 27 — 27 Total non-current assets 14,555 (2,148) 12,407 Current assets Trade and other receivables 268 — 268 Financial and other investments 69 — 69 Cash 44 — 44 Other current assets 42 — 42 Total current assets 423 — 423 Total assets 14,978 (2,148) 12,830 Current liabilities Borrowings (730) — (730) Trade and other payables (531) 48 (483) Other current liabilities (35) — (35) Total current liabilities (1,296) 48 (1,248) Non-current liabilities Borrowings (5,967) (1,589) (7,556) Deferred tax (1,013) 224 (789) Contract liabilities (2,706) 2,706 — Other non-current liabilities (56) (21) (77) Total non-current liabilities (9,742) 1,320 (8,422) Total liabilities (11,038) 1,368 (9,670) Total identifiable net assets 3,940 (780) 3,160 Goodwill 1,254 3,467 4,721 Total consideration transferred 5,194 2,687 7,881 Satisfied by: Cash consideration 7,881 Total consideration transferred 7,881 37. Acquisitions continued The goodwill arising from the acquisition represents the future expected growth in the WPD business, the benefits that are expected to be achieved as a result of the combination of the two businesses and the expertise of the management team acquired. No component of goodwill qualifies for recognition as a separate tangible or intangible asset. The goodwill is not deductible for tax purposes and at the acquisition date, there were no material contingent liabilities. The fair value of trade and other receivables of £270 million includes trade receivables with a fair value of £86 million. The gross contractual amount for trade receivables due is £103 million, of which £17 million was expected to be uncollectible. Total acquisition-related costs of £110 million were recognised within Other operating income and costs, of which £15 million was recognised in the year ended 31 March 2021 and £95 million in the year ended 31 March 2022.

Post balance sheet events

Post balance sheet events	12 Months Ended
	Mar. 31, 2022
Events After Reporting Period [Abstract]
Post balance sheet events	38. Post balance sheet events On 6 April 2022, the UK government announced that the entirety of ESO will become part of an independent system operator public body, following the Future System Operator (FSO) consultation. The FSO, which is subject to legislative approval, will take on a number of key roles in electricity and gas in Great Britain. The Group is working closely with BEIS and Ofgem to plan and prepare for the implementation of the changes required to create the FSO. On 11 May 2022, Ofgem approved the Group’s request to return £200 million of interconnector revenue subject to the cap and floor regime to consumers ahead of schedule (see note 26). This return will take place over the next two years. The Group is now working through the formal steps outlined under the regulatory framework which will result in the finalisation of the mechanism by which the revenues will be returned.

Basis of preparation and rece_2

Basis of preparation and recent accounting developments (Policies)	12 Months Ended
	Mar. 31, 2022
Accounting Policies, Changes In Accounting Estimates And Errors [Abstract]
Description of accounting policy for basis of preparation	These consolidated financial statements have been prepared in accordance with International Accounting Standards (IAS) and International Financial Reporting Standards (IFRS) and related interpretations as issued by the IASB and IFRS as adopted by the UK. They are prepared on the basis of all IFRS accounting standards and interpretations that are mandatory for the period ended 31 March 2022 and in accordance with the Companies Act 2006. The comparative financial information has also been prepared on this basis. The consolidated financial statements have been prepared on a historical cost basis, except for the recording of pension assets and liabilities, the revaluation of derivative financial instruments and certain commodity contracts and certain financial assets and liabilities measured at fair value. These consolidated financial statements are presented in pounds sterling, which is also the functional currency of the Company. The notes to the financial statements have been prepared on a continuing basis unless otherwise stated.
Going concern	As part of the Directors’ consideration of the appropriateness of adopting the going concern basis of accounting in preparing these financial statements, the Directors have considered the impact of the planned disposals of The Narragansett Electric Company (NECO) and the UK Gas Transmission business (see note 10) and the financing for the acquisition of PPL Western Power Distribution (WPD) (see note 33). The Directors have assessed the principal risks, including by modelling both a base case and a reasonable worst-case scenario. The main cash flow impacts identified in the reasonable worst-case scenario are: • additional potential working capital requirements in response to energy price increases driven by the wider energy market stability challenges and the conflict between Russia and Ukraine; • adverse impacts of inflation on our capex programme; • adverse impact from timing across the Group, i.e. a net under-recovery of allowed revenues or reductions in over-collections; • a significant reduction in cash collections driven by lower customer demand and increased bad debt in our US businesses and potential supplier defaults in our UK business; • higher cash outflow than expected following the Sellindge Interconnector fire; • higher operating costs than expected; or non-delivery of planned efficiencies across the Group; and • the potential impact of further significant storm costs in the US. As part of their analysis, the Board also considered the following potential levers at their discretion to improve the position identified by the analysis if the debt capital markets are not accessible: • the payment of dividends to shareholders; • significant changes in the phasing of the Group’s capital programme, with elements of non-essential works and programmes delayed; and • a number of further reductions in operating expenditure across the Group primarily related to workforce cost reductions in both the UK and the US. Having considered the reasonable worst-case scenario, the impact and timing of the planned strategic transactions, and the further levers at the Board’s discretion, the Group continues to have headroom against the Group’s committed facilities identified in note 33 to the financial statements. In addition to the above, the ability to raise new and extend existing financing was separately included in the analysis, and the Directors noted the c.£4.2 billion of new long-term senior debt issued in the period from 1 April to 31 March 2022 as evidence of the Group’s ability to continue to have access to the debt capital markets if needed. Based on the above, the Directors have concluded the Group is well placed to manage its financing and other business risks satisfactorily and have a reasonable expectation that the Group will have adequate resources to continue in operation for at least 12 months from the signing date of these consolidated financial statements. They therefore consider it appropriate to adopt the going concern basis of accounting in preparing the financial statements.
Basis of consolidation	The consolidated financial statements incorporate the results, assets and liabilities of the Company and its subsidiaries, together with a share of the results, assets and liabilities of joint operations. A subsidiary is defined as an entity controlled by the Group. Control is achieved where the Group is exposed to, or has the rights to, variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. The Group accounts for joint ventures and associates using the equity method of accounting, where the investment is carried at cost plus post-acquisition changes in the share of net assets of the joint venture or associate, less any provision for impairment. Losses in excess of the consolidated interest in joint ventures and associates are not recognised, except where the Company or its subsidiaries have made a commitment to make good those losses. Where necessary, adjustments are made to bring the accounting policies used in the individual financial statements of the Company, subsidiaries, joint operations, joint ventures and associates into line with those used by the Group in its consolidated financial statements under IFRS. Intercompany transactions are eliminated. The results of subsidiaries, joint operations, joint ventures and associates acquired or disposed of during the year are included in the consolidated income statement from the effective date of acquisition or up to the effective date of disposal, as appropriate. Acquisitions are accounted for using the acquisition method, where the purchase price is allocated to the identifiable assets acquired and liabilities assumed on a fair value basis and the remainder recognised as goodwill.
Foreign currencies	Transactions in currencies other than the functional currency of the Company or subsidiary concerned are recorded at the rates of exchange prevailing on the dates of the transactions. At each reporting date, monetary assets and liabilities that are denominated in foreign currencies are retranslated at closing exchange rates. Non-monetary assets are not retranslated unless they are carried at fair value. Gains and losses arising on the retranslation of monetary assets and liabilities are included in the income statement, except where the application of hedge accounting requires inclusion in other comprehensive income (see note 32(e)). On consolidation, the assets and liabilities of operations that have a functional currency different from the Company’s functional currency of pounds sterling, principally our US operations that have a functional currency of US dollars, are translated at exchange rates prevailing at the reporting date. Income and expense items are translated at the average exchange rates for the period where these do not differ materially from rates at the date of the transaction. Exchange differences arising are recognised in other comprehensive income and transferred to the consolidated translation reserve within other equity reserves (see note 28).
Disposal of The Naragansett Electric Company and UK Gas Transmission	As described further in note 10, on 17 March 2021, the Group signed an agreement to sell 100% of the share capital of a wholly owned subsidiary, NECO. Whilst all of the regulatory approvals are in place, the disposal of NECO was not finalised as at 31 March 2022 due to the appeal of one of these approvals by the Rhode Island Attorney General. The associated assets and liabilities have been presented as held for sale in the consolidated statement of financial position. As NECO does not represent either a major line of business or a geographical area of operations, it has not met the criteria for classification as a discontinued operation and therefore its results for the period are not separately disclosed on the face of the income statement. E. Disposal of UK Gas Transmission As described further in note 10, on 27 March 2022, the Group agreed to sell 100% of the UK Gas Transmission business to a new entity (the ‘Acquiring Entity’) in exchange for £4.2 billion cash consideration (subject to customary completion adjustments) and a 40% interest in the Acquiring Entity. The sale is expected to complete in the third quarter of the financial year ending 31 March 2023 subject to the receipt of all regulatory approvals. The Group’s 40% interest in the Acquiring Entity is expected to be classified as an associate on the basis that the Group will retain significant influence over the business through its retained stake. The Group has the ability to appoint two out of the seven Directors to the Board of the Acquiring Entity. On 27 March 2022, the Group also entered into a Further Acquisition Agreement (FAA) for the potential sale of the remaining 40% stake. The FAA is a put option that can be exercised by the purchaser either in the period between 1 January and 31 March 2023 or in the period between 1 April and 30 June 2023. The deferral of the option window is at our discretion (subject to change depending on the timing of the closing of the sale agreement).
Areas of judgement and key sources of estimation uncertainty	The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities, and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from these estimates. Information about such judgements and estimations is in the notes to the financial statements, and the key areas are summarised below. Areas of judgement that have the most significant effect on the amounts recognised in the financial statements are as follows: • in relation to the planned disposal of the UK Gas Transmission business, the key judgement that has been applied is the date from which the business qualified for classification as held for sale and a discontinued operation, as explained further in note 10; • in performing the WPD goodwill and indefinite-lived licence intangible assets impairment assessment, judgement has been applied over the forecast cash flow duration (see note 11); and • the judgement that, notwithstanding legislation enacted and targets committing the UK, New York State and Massachusetts to achieving net zero greenhouse gas emissions by 2050, these do not trigger a reassessment of the remaining useful economic lives of our gas network assets (see key sources of estimation uncertainty below and note 13). Key sources of estimation uncertainty that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year are as follows: • in performing the goodwill impairment assessment of the WPD group of cash-generating units, the key source of estimation uncertainty relates to the discount rate and terminal value assumptions used in the value-in-use calculations (see note 11); • the valuation of liabilities for pensions and other post-retirement benefits (see note 25); and • the cash flows applied in determining the environmental provisions, in particular relating to three US Superfund sites (see note 26). 1. Basis of preparation and recent accounting developments continued
Accounting policy choices	IFRS provides certain options available within accounting standards. Choices we have made, and continue to make, include the following: • Presentational formats: we use the nature of expense method for our income statement and aggregate our statement of financial position to net assets and total equity. • Financial instruments: we normally opt to apply hedge accounting in most circumstances where this is permitted (see note 32(e)).
New IFRS accounting standards and interpretations effective for the year ended 31 March 2021 and New IFRS accounting standards and interpretations not yet adopted	The Group early adopted the following amendments to standards which have had no material impact on the Group’s results or financial statement disclosures: • amendments to IFRS 16 ‘Leases – COVID-19-Related Rent Concessions’; • amendments to IFRS 3 ‘Definition of a Business’; and • amendments to IAS 1 and IAS 8 ‘Definition of Material’. In April 2021, the IFRS IC (Interpretation Committee) also issued an agenda decision in relation to the accounting treatment for configuration and customisation costs in a cloud computing arrangement. This guidance clarified that in order for an intangible asset to be capitalised in relation to customisation and configuration costs in a cloud computing arrangement, it is necessary for there to be control of the underlying software asset or for there to be a separate intangible asset which meets the definition in IAS 38 Intangible Assets. As at 31 March 2022, the Group has recognised a cumulative adjustment against software intangible assets of £34 million for previously capitalised customisation and configuration relating to its continuing operations. The Group has also considered the application of the new accounting guidance for its comparative periods and concluded that it does not have a material impact. Accordingly, no comparative periods have been restated. The following new accounting standards and amendments to existing standards have been issued but are not yet effective: • IFRS 17 ‘Insurance Contracts’; • amendments to IFRS 3 ‘Business Combinations’; • amendments to IAS 12 ‘Deferred Tax Related to Assets and Liabilities Arising from a Single Transaction’; • amendments to IAS 16 ‘Property, Plant and Equipment’; • amendments to IAS 37 ‘Provisions, Contingent Liabilities and Contingent Assets’; • amendments to IAS 1 ‘Presentation of Financial Statements’; • amendments to IAS 8 ‘Accounting Policies, Changes in Accounting Estimates and Errors’; • annual improvements to IFRS standards 2018-2020; and • amendments to IFRS Practice Statement 2 – making materiality judgements. The Group is currently assessing the impact of the above standards, but they are not expected to have a material impact. The Group has not adopted any other standard, amendment or interpretation that has been issued but is not yet effective.
Segmental analysis	This note sets out the financial performance for the year split into the different parts of the business (operating segments). The performance of these operating segments is monitored and managed on a day-to-day basis. Revenue and the results of the business are analysed by operating segment, based on the information the Board of Directors uses internally for the purposes of evaluating the performance of each operating segment and determining resource allocation between them. The Board is National Grid’s chief operating decision maker (as defined by IFRS 8 ‘Operating Segments’) and assesses the profitability of operations principally on the basis of operating profit before exceptional items and remeasurements (see note 5). As a matter of course, the Board also considers profitability by segment, excluding the effect of timing. However, the measure of profit disclosed in this note is operating profit before exceptional items and remeasurements as this is the measure that is most consistent with the IFRS results reported within these financial statements.
Revenue	Revenue arises in the course of ordinary activities and principally comprises: • transmission services; • distribution services; and • generation services. Transmission services, distribution services and certain other services (excluding rental income but including metering) fall within the scope of IFRS 15 ‘Revenue from Contracts with Customers’, whereas generation services (which solely relate to the contract with the Long Island Power Authority (LIPA) in the US) are accounted for under IFRS 16 ‘Leases’ as rental income, also presented within revenue. Revenue is recognised to reflect the transfer of goods or services to customers at an amount that reflects the consideration to which the Group expects to be entitled to in exchange for those goods or services and excludes amounts collected on behalf of third parties and value added tax. The Group recognises revenue when it transfers control over a product or service to a customer.
Other operating income and costs	Below we have presented separately certain items included in our operating costs from continuing operations. These include a breakdown of payroll costs (including disclosure of amounts paid to key management personnel) and fees paid to our auditors. Other operating income includes gains arising on disposal of interests in other entities.
Exceptional items and remeasurements	To monitor our segmental financial performance, we use a profit measure that excludes certain income and expenses. We call that measure ‘adjusted profit’. Adjusted profit (which excludes exceptional items and remeasurements as defined below) is used by management to monitor financial performance as it is considered that it aids the comparability of our reported financial performance from year to year. We exclude items from adjusted profit because, if included, these items could distort understanding of our performance for the year and the comparability between periods. This note analyses these items, which are included in our results for the year but are excluded from adjusted profit.
Finance income and costs	This note details the interest income generated by our financial assets and interest expense incurred on our financial liabilities, primarily our financing portfolio (including our financing derivatives). It also includes the net interest on our pensions and other post-retirement assets. In reporting adjusted profit, we adjust net financing costs to exclude any net gains or losses on financial instruments included in remeasurements (see note 5).
Tax	Tax is payable in the territories where we operate, mainly the UK and the US. This note gives further details of the total tax charge and tax liabilities, including current and deferred tax. The current tax charge is the tax payable on this year’s taxable profits. Deferred tax is an accounting adjustment to provide for tax that is expected to arise in the future due to differences in the accounting and tax bases.
Earnings per share (EPS)	EPS is the amount of profit after tax attributable to each ordinary share. Basic EPS is calculated on profit after tax for the year attributable to equity shareholders divided by the weighted average number of shares in issue during the year. Diluted EPS shows what the impact would be if all outstanding share options were exercised and treated as ordinary shares at year end. The weighted average number of shares is increased by additional shares issued as scrip dividends and reduced by shares repurchased by the Company during the year. The earnings per share calculations are based on profit after tax attributable to equity shareholders of the Company which excludes non-controlling interests.
Discontinued operations and assets held for sale	The results and cash flows of significant assets or businesses sold during the year are shown separately from our continuing operations, and presented within discontinued operations in the income statement and cash flow statement. Assets and businesses are classified as held for sale when their carrying amounts are recovered through sale rather than through continuing use. They only meet the held for sale condition when the assets are ready for immediate sale in their present condition, management is committed to the sale and it is highly probable that the sale will complete within one year. Depreciation ceases on assets and businesses when they are classified as held for sale and the assets and businesses are impaired if the proceeds less sale costs fall short of the carrying value.
Goodwill	Goodwill represents the excess of what we paid to acquire businesses over the fair value of their net assets at the acquisition date. We assess whether goodwill is recoverable by performing an impairment review annually or more frequently if events or changes in circumstances indicate a potential impairment.
Other intangible assets	Other intangible assets include software which is written down (amortised) over the period we expect to receive a benefit from the asset. An amortisation expense is charged to the income statement to reflect the reduced value of the asset over time. Amortisation is calculated by estimating the number of years we expect the asset to be used (useful economic life or UEL) and charging the cost of the asset to the income statement equally over this period. Indefinite-lived intangibles comprise regulatory licences for which there is no foreseeable limit to the period over which they are expected to generate net cash inflows. These assets are considered to have an indefinite life and are not amortised but subject to a review for impairment annually, or more frequently if events or circumstances indicate a potential impairment. Any impairment is charged to the income statement as it arises.
Property, plant and equipment	Property, plant and equipment are the physical assets controlled by us. The cost of these assets primarily represents the amount initially paid for them or the fair value on the date of acquisition of a business. Cost includes both their purchase price and the construction and other costs associated with getting them ready for operation. A depreciation expense is charged to the income statement to reflect annual wear and tear and the reduced value of the asset over time. Depreciation is calculated by estimating the number of years we expect the asset to be used (useful economic life or UEL) and charging the cost of the asset to the income statement equally over this period. We operate an energy networks business and therefore have a significant physical asset base. We continue to invest in our networks to maintain reliability, create new customer connections and ensure our networks are flexible and resilient. Our business plan envisages these additional investments will be funded through a mixture of cash generated from operations and the issue of new debt.
Other non-current assets	Other non-current assets include assets that do not fall into any other non-current asset category (such as goodwill or property, plant and equipment) where the benefit to be received from the asset is not due to be received until after 31 March 2023.
Financial and other investments	The Group holds a range of financial and other investments. These investments include short-term money market funds, quoted investments in equities or bonds of other companies, investments in our venture capital portfolio (National Grid Partners), bank deposits with a maturity of greater than three months, and investments that can not be readily used in operations, principally collateral deposited in relation to derivatives.
Investments in joint ventures and associates	Investments in joint ventures and associates represent businesses we do not control but over which we exercise joint control or significant influence. They are accounted for using the equity method. A joint venture is an arrangement established to engage in economic activity, which the Group jointly controls with other parties and has rights to a share of the net assets of the arrangement. An associate is an entity which is neither a subsidiary nor a joint venture, but over which the Group has significant influence.
Derivative financial instruments	Derivatives are financial instruments that derive their value from the price of an underlying item such as interest rates, foreign exchange rates, credit spreads, commodities, equities or other indices. In accordance with policies approved by the Board, derivatives are transacted generally to manage exposures to fluctuations in interest rates, foreign exchange rates and commodity prices. Our derivatives balances comprise two broad categories: • financing derivatives: These are used to manage our exposure to interest rates and foreign exchange rates. Specifically, we use these derivatives to manage our financing portfolio, holdings in foreign operations and contractual operational cash flows; and • commodity contract derivatives: These are used to manage our US customers’ exposure to price and supply risks. Some forward contracts for the purchase of commodities meet the definition of derivatives. We also enter into derivative financial instruments linked to commodity prices, including index futures, options and swaps, which are used to manage market price volatility.
Inventories and current intangible assets	Inventories represent assets that we intend to use in order to generate revenue in the short term, either by selling the asset itself (for example, fuel stocks) or by using it to fulfil a service to a customer or to maintain our network (consumables).
Trade and other receivables	Trade and other receivables include amounts which are due from our customers for services we have provided, accrued income which has not yet been billed, prepayments, contract assets where certain milestones are required to be fulfilled and other receivables that are expected to be settled within 12 months.
Cash and cash equivalents	Cash and cash equivalents include cash balances, together with short-term investments with an original maturity of less than three months that are readily convertible to cash.
Borrowings	We borrow money primarily in the form of bonds and bank loans. These are for a fixed term and may have fixed or floating interest rates or are linked to inflation indices. We use derivatives to manage risks associated with interest rates, inflation rates and foreign exchange. Lease liabilities are also included within borrowings. Our price controls and rate plans lead us to fund our networks within a certain ratio of debt to equity or regulatory asset value and, as a result, we have issued a significant amount of debt. As we continue to invest in our networks, the value of debt is expected to increase over time. To maintain a strong balance sheet and to allow us to access capital markets at commercially acceptable interest rates, we balance the amount of debt we issue with the value of our assets, and we take account of certain other metrics used by credit rating agencies.
Trade and other payables	Trade and other payables include amounts owed to suppliers, tax authorities and other parties which are due to be settled within 12 months. The total also includes deferred amounts, some of which represent monies received from customers but for which we have not yet delivered the associated service. These amounts are recognised as revenue when the service is provided.
Contract liabilities	Contract liabilities primarily relate to the advance consideration received from customers for construction contracts, mainly in relation to connections, for which revenue is recognised over the life of the asset.
Other non-current liabilities	Other non-current liabilities include deferred income and customer contributions which will not be recognised as income until after 31 March 2023. It also includes contingent consideration and other payables that are not due until after that date.
Pensions and other post-retirement benefits	All of our employees are eligible to participate in a pension plan. We have defined contribution (DC) and defined benefit (DB) pension plans in the UK and the US. In the US we also provide healthcare and life insurance benefits to eligible employees, post-retirement. The fair value of associated plan assets and present value of DB obligations are updated annually in accordance with IAS 19 ‘Employee Benefits’. We separately present our UK and US pension plans to show the geographical split. Below we provide a more detailed analysis of the amounts recorded in the primary financial statements and the actuarial assumptions used to value the DB obligations.
Provisions	Provisions are recognised when an obligation exists resulting from a past event, and it is probable that cash will be paid to settle it, but the exact amount of cash required can only be estimated. The majority of our provisions relate to environmental remediation, specifically in relation to certain Superfund sites in the US, being sites we own or have owned in the past where hazardous substances are present as a result of the historic operations of manufactured gas plants in Brooklyn, New York. We also recognise provisions for decommissioning costs for various assets we would be required to remove at the end of their lives; the costs associated with restructuring plans; the costs in respect of insured past events; for certain Ofgem arrangements in respect of specific interconnectors which require the return of excess revenues above a cap; and for lease contracts we have entered into that are now loss-making. In determining the quantum of the provision we recognise, we make estimates in relation to management’s best judgement of the evaluation of the likelihood and the probability of exposure to potential loss, and the costs that would be incurred. Should circumstances change following unforeseeable developments, the likelihood or quantum could alter.
Share capital	Ordinary share capital represents the total number of shares issued which are publicly traded. We also disclose the number of treasury shares the Company holds, which are shares that the Company has bought itself, predominantly to actively manage scrip issuances and settle employee share option and reward plan liabilities.
Other equity reserves	Other equity reserves are different categories of equity as required by accounting standards and represent the impact of a number of our historical transactions or fair value movements on certain financial instruments that the Company holds.
Net debt	We define net debt as the amount of borrowings and financing derivatives less cash and current financial investments.
Commitments and contingencies	Commitments are those amounts that we are contractually required to pay in the future as long as the other party meets its obligations. These commitments primarily relate to energy purchase agreements and contracts for the purchase of assets which, in many cases, extend over a long period of time. We also disclose any contingencies, which include guarantees that companies have given, where we pledge assets against current obligations that will remain for a specific period.Contingent assets are disclosed where the Group concludes that an inflow of economic benefits is probable.
Related party transactions	Related parties include joint ventures, associates, investments and key management personnel.
Financial risk management	Our activities expose us to a variety of financial risks including credit risk, liquidity risk, capital risk, currency risk, interest rate risk, inflation risk and commodity price risk. Our risk management programme focuses on the unpredictability of financial markets and seeks to minimise potential volatility of financial performance from these risks. We use financial instruments, including derivative financial instruments, to manage these risks.
Borrowing facilities	We borrow money primarily in the form of bonds and bank loans. These are for a fixed term and may have fixed or floating interest rates or are linked to inflation indices. We use derivatives to manage risks associated with interest rates, inflation rates and foreign exchange. Lease liabilities are also included within borrowings. Our price controls and rate plans lead us to fund our networks within a certain ratio of debt to equity or regulatory asset value and, as a result, we have issued a significant amount of debt. As we continue to invest in our networks, the value of debt is expected to increase over time. To maintain a strong balance sheet and to allow us to access capital markets at commercially acceptable interest rates, we balance the amount of debt we issue with the value of our assets, and we take account of certain other metrics used by credit rating agencies.
Subsidiary undertakings, joint ventures and associates	Investments in joint ventures and associates represent businesses we do not control but over which we exercise joint control or significant influence. They are accounted for using the equity method. A joint venture is an arrangement established to engage in economic activity, which the Group jointly controls with other parties and has rights to a share of the net assets of the arrangement. An associate is an entity which is neither a subsidiary nor a joint venture, but over which the Group has significant influence.
Sensitivities	In order to give a clearer picture of the impact on our results or financial position of potential changes in significant estimates and assumptions, the following sensitivities are presented. These sensitivities are based on assumptions and conditions prevailing at the year end and should be used with caution. The effects provided are not necessarily indicative of the actual effects that would be experienced because our actual exposures are constantly changing.
Additional disclosures in respect of guaranteed securities	Niagara Mohawk Power Corporation, a wholly owned subsidiary of the Group, has issued preferred shares that are listed on a US national securities exchange and are guaranteed by National Grid plc. This guarantor commits to honour any liabilities should the company issuing the debt have any financial difficulties. In order to provide debt holders with information on the financial stability of the company providing the guarantee, we are required to disclose individual financial information for this company. We have chosen to include this information in the Group financial statements rather than submitting separate stand-alone financial statements.

Segmental analysis (Tables)

Segmental analysis (Tables)	12 Months Ended
	Mar. 31, 2022
Disclosure of operating segments [abstract]
Schedule of activities, revenue, operating profit and capital expenditure by operating segments	The following table describes the main activities for each reportable operating segment within continuing operations: UK Electricity Transmission The high-voltage electricity transmission networks in England and Wales. UK Electricity Distribution The electricity distribution networks of WPD in the East Midlands, West Midlands and South West of England and South Wales. UK Electricity System Operator The Great Britain system operator. New England Gas distribution networks, electricity distribution networks and high-voltage electricity transmission networks in New England. New York Gas distribution networks, electricity distribution networks and high-voltage electricity transmission networks in New York. 2022 2021¹ 2020¹ Total £m Sales between segments £m Sales to third parties £m Total Sales Sales Total Sales Sales Operating segments – continuing operations: UK Electricity Transmission 2,035 (7) 2,028 1,974 (10) 1,964 1,986 (8) 1,978 UK Electricity Distribution 1,482 (14) 1,468 — — — — — — UK Electricity System Operator 3,455 (18) 3,437 2,018 — 2,018 1,716 — 1,716 New England 4,550 — 4,550 4,214 — 4,214 4,235 — 4,235 New York 5,561 — 5,561 4,605 — 4,605 4,601 — 4,601 NGV and Other 1,405 — 1,405 864 — 864 834 (4) 830 Total revenue from continuing operations 18,488 (39) 18,449 13,675 (10) 13,665 13,372 (12) 13,360 Split by geographical areas – continuing operations: UK 7,803 4,368 4,102 US 10,646 9,297 9,258 Total revenue from continuing operations 18,449 13,665 13,360 1. Comparative amounts have been re-presented to reflect the new operating segments and the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 2. In connection with the disposal of St William Homes LLP in the year the Group released deferred income within NGV and Other of £189 million related to deferred profits from previous property sales (see note 5). 2. Segmental analysis continued (b) Operating profit A reconciliation of the operating segments’ measure of profit to profit before tax from continuing operations is provided below. Further details of the exceptional items and remeasurements are provided in note 5. Before exceptional items Exceptional items and remeasurements After exceptional items and remeasurements 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ £m £m £m £m £m £m £m £m £m Operating segments – continuing operations: UK Electricity Transmission 1,067 1,094 1,109 (12) (14) (5) 1,055 1,080 1,104 UK Electricity Distribution 909 — — — — — 909 — — UK Electricity System Operator 7 (60) 211 (2) 7 1 5 (53) 212 New England 743 611 523 21 3 (53) 764 614 470 New York 780 665 835 315 30 (465) 1,095 695 370 NGV and Other 307 117 126 236 (52) (3) 543 65 123 Total operating profit from continuing operations 3,813 2,427 2,804 558 (26) (525) 4,371 2,401 2,279 Split by geographical area – continuing operations: UK 2,234 1,113 1,422 224 (57) (8) 2,458 1,056 1,414 US 1,579 1,314 1,382 334 31 (517) 1,913 1,345 865 Total operating profit from continuing operations 3,813 2,427 2,804 558 (26) (525) 4,371 2,401 2,279 1. Comparative amounts have been re-presented to reflect the new operating segments and the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. Before exceptional items Exceptional items After exceptional items 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ £m £m £m £m £m £m £m £m £m Reconciliation to profit before tax: Operating profit from continuing operations 3,813 2,427 2,804 558 (26) (525) 4,371 2,401 2,279 Share of post-tax results of joint ventures and associates 148 66 88 (56) (8) (1) 92 58 87 Finance income 65 35 70 (15) 23 (16) 50 58 54 Finance costs (1,146) (900) (999) 74 47 (21) (1,072) (853) (1,020) Profit before tax from continuing operations 2,880 1,628 1,963 561 36 (563) 3,441 1,664 1,400 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. (c) Capital expenditure Capital expenditure represents additions to property, plant and equipment and non-current intangibles but excludes additional investments in and loans to joint ventures and associates. Net book value of property, plant and Capital expenditure Depreciation, amortisation 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ 2022 2021¹ 2020¹ £m £m £m £m £m £m £m £m £m Operating segments: UK Electricity Transmission 14,678 14,000 13,463 1,195 984 951 (508) (460) (431) UK Electricity Distribution 12,522 — — 899 — — (158) — — UK Electricity System Operator 404 379 336 108 88 92 (83) (47) (38) New England 11,485 10,165 13,127 1,561 1,437 1,365 (364) (389) (373) New York 18,676 16,467 16,920 1,960 1,738 1,822 (537) (453) (436) NGV and Other 3,039 2,750 2,490 462 480 562 (180) (136) (157) Total 60,804 43,761 46,336 6,185 4,727 4,792 (1,830) (1,485) (1,435) Split by geographical area – continuing operations: UK 30,131 16,627 15,706 2,546 1,504 1,560 (879) (596) (579) US 30,673 27,134 30,630 3,639 3,223 3,232 (951) (889) (856) Total 60,804 43,761 46,336 6,185 4,727 4,792 (1,830) (1,485) (1,435) Asset type: Property, plant and equipment 57,532 42,424 45,160 5,714 4,335 4,465 (1,544) (1,317) (1,286) Non-current intangible assets 3,272 1,337 1,176 471 392 327 (286) (168) (149) Total 60,804 43,761 46,336 6,185 4,727 4,792 (1,830) (1,485) (1,435)

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Mar. 31, 2022
Disclosure of disaggregation of revenue from contracts with customers [abstract]
Disclosure of disaggregation of revenue by primary geographical market and major service lines	In the following tables, revenue is disaggregated by primary geographical market and major service lines. The table below reconciles disaggregated revenue with the Group’s reportable segments (see note 2). Revenue for the year ended 31 March 2022 UK Electricity Transmission UK Electricity Distribution UK Electricity System Operator New New NGV and Other Total Revenue under IFRS 15 Transmission 1,983 — — 52 405 627 3,067 Distribution — 1,375 — 4,434 5,110 — 10,919 System Operator — — 3,418 — — — 3,418 Other 1 35 89 19 10 10 147 310 Total IFRS 15 revenue 2,018 1,464 3,437 4,496 5,525 774 17,714 Other revenue Generation — — — — — 373 373 Other 2 10 4 — 54 36 258 362 Total other revenue 10 4 — 54 36 631 735 Total revenue from continuing operations 2,028 1,468 3,437 4,550 5,561 1,405 18,449 1. The UK Electricity Transmission and UK Electricity Distribution other IFRS 15 revenue principally relates to engineering recharges, which are the recovery of costs incurred for construction work requested by customers, such as the rerouting of existing network assets. UK Electricity System Operator other IFRS 15 revenue reflects the net income from its role as agent in respect of transmission network revenues. Within NGV and Other, the other IFRS 15 revenue principally relates to revenue generated from our NG Renewables business. 2. Other revenue, recognised in accordance with accounting standards other than IFRS 15, includes property sales by our UK commercial property business and rental income. 3. Revenue continued (g) Disaggregation of revenue continued Geographical split for the year ended 31 March 2022 UK Electricity Transmission UK Electricity Distribution UK Electricity System Operator New England New NGV and Total Revenue under IFRS 15 UK 2,018 1,464 3,437 — — 646 7,565 US — — — 4,496 5,525 128 10,149 Total IFRS 15 revenue 2,018 1,464 3,437 4,496 5,525 774 17,714 Other revenue UK 10 4 — — — 224 238 US — — — 54 36 407 497 Total other revenue 10 4 — 54 36 631 735 Total revenue from continuing operations 2,028 1,468 3,437 4,550 5,561 1,405 18,449 Revenue for the year ended 31 March 2021 UK Electricity Transmission UK Electricity Distribution UK Electricity System Operator New New NGV and Total¹ Revenue under IFRS 15 Transmission 1,875 — — 74 329 316 2,594 Distribution — — — 4,091 4,226 — 8,317 System Operator — — 2,076 — — — 2,076 Other 2 67 — (61) 8 7 76 97 Total IFRS 15 revenue 1,942 — 2,015 4,173 4,562 392 13,084 Other revenue Generation — — — — — 376 376 Other 3 22 — 3 41 43 96 205 Total other revenue 22 — 3 41 43 472 581 Total revenue from continuing operations 1,964 — 2,018 4,214 4,605 864 13,665 Geographical split for the year ended 31 March 2021 UK Electricity Transmission £m UK Electricity Distribution UK Electricity System Operator New New NGV and Total¹ Revenue under IFRS 15 UK 1,942 — 2,015 — — 327 4,284 US — — — 4,173 4,562 65 8,800 Total IFRS 15 revenue 1,942 — 2,015 4,173 4,562 392 13,084 Other revenue UK 22 — 3 — — 59 84 US — — — 41 43 413 497 Total other revenue 22 — 3 41 43 472 581 Total revenue from continuing operations 1,964 — 2,018 4,214 4,605 864 13,665 1. Comparative amounts have been re-presented to reflect the new operating segments and the classification of the UK Gas Transmission business as a discontinued operation. See notes 1, 2 and 10 for further information. 2. The UK Electricity Transmission other IFRS 15 revenue principally relates to engineering recharges, which are the recovery of costs incurred for construction work requested by customers, such as the rerouting of existing network assets. UK Electricity System Operator other IFRS 15 revenue reflects the net income from its role as agent in respect of transmission network revenues. Within NGV and Other, the other IFRS 15 revenue principally relates to revenue generated from our NG Renewables business. 3. Other revenue, recognised in accordance with accounting standards other than IFRS 15, principally includes property sales by our UK commercial property business and rental income reported in NGV and Other. 3. Revenue continued (g) Disaggregation of revenue continued Revenue for the year ended 31 March 2020 UK Electricity Transmission UK Electricity Distribution UK Electricity System Operator New New NGV and Total¹ Revenue under IFRS 15 Transmission 1,898 — — 77 348 309 2,632 Distribution — — — 4,114 4,205 — 8,319 System Operator — — 1,610 — — — 1,610 Other 2 69 — 94 6 6 51 226 Total IFRS 15 revenue 1,967 — 1,704 4,197 4,559 360 12,787 Other revenue Generation — — — — — 369 369 Other 3 11 — 12 38 42 101 204 Total other revenue 11 — 12 38 42 470 573 Total revenue from continuing operations 1,978 — 1,716 4,235 4,601 830 13,360 Geographical split for the year ended 31 March 2020 UK Electricity Transmission £m UK Electricity Distribution UK Electricity System Operator New New NGV and Total¹ Revenue under IFRS 15 UK 1,967 — 1,704 — — 322 3,993 US — — — 4,197 4,559 38 8,794 Total IFRS 15 revenue 1,967 — 1,704 4,197 4,559 360 12,787 Other revenue UK 11 — 12 — — 86 109 US — — — 38 42 384 464 Total other revenue 11 — 12 38 42 470 573 Total revenue from continuing operations 1,978 — 1,716 4,235 4,601 830 13,360 1. Comparative amounts have been re-presented to reflect the new operating segments and the classification of the UK Gas Transmission business as a discontinued operation. See notes 1, 2 and 10 for further information. 2. The UK Electricity Transmission other IFRS 15 revenue principally relates to engineering recharges, which are the recovery of costs incurred for construction work requested by customers, such as the rerouting of existing network assets. UK Electricity System Operator other IFRS 15 revenue reflects the net income from its role as agent in respect of transmission network revenues. Within NGV and Other, the other IFRS 15 revenue principally relates to revenue generated from our NG Renewables business. 3. Other revenue, recognised in accordance with accounting standards other than IFRS 15, principally includes property sales by our UK commercial property business and rental income reported in NGV and Other.

Other operating income and co_2

Other operating income and costs (Tables)	12 Months Ended
	Mar. 31, 2022
Analysis of income and expense [abstract]
Schedule of expenses by nature	2022 2021¹ 2020¹ £m £m £m (Gain) on disposal of St William Homes LLP (note 5) (228) — — Depreciation, amortisation and impairment 1,830 1,485 1,435 Payroll costs 1,794 1,638 1,558 Purchases of electricity 1,280 1,130 1,403 Purchases of gas 1,666 1,250 1,316 Property and other taxes 1,202 1,105 1,100 UK Electricity Balancing costs 3,152 1,875 1,317 Other 3,215 2,456 2,718 Other operating (income)/costs 13,911 10,939 10,847 Provision for bad and doubtful debts 167 325 234 Total operating costs from continuing operations 14,078 11,264 11,081 Operating costs from continuing operations include: Inventory consumed 436 312 315 Research and development expenditure 11 12 9 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. (a) Payroll costs 2022 2021¹ 2020¹ £m £m £m Wages and salaries 2 2,563 2,170 2,081 Social security costs 201 156 152 Defined contribution scheme costs 81 67 62 Defined benefit pension costs 185 126 125 Share-based payments 38 23 16 Severance costs (excluding pension costs) 5 9 1 3,073 2,551 2,437 Less: payroll costs capitalised (1,279) (913) (879) Total payroll costs from continuing operations 1,794 1,638 1,558 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 2. Included within wages and salaries are US other post-retirement benefit costs of £39 million (2021: £43 million; 2020: £45 million). For further information refer to note 25.
Schedule of additional information	(b) Number of employees 31 March 2022 Monthly average 2022 31 March 2021¹ Monthly average 2021 1 31 March 2020¹ Monthly average 2020 1 UK 11,960 11,393 4,468 4,333 4,185 4,095 US 17,332 17,314 17,026 16,821 16,748 16,679 Total number of employees (continuing operations) 29,292 28,707 21,494 21,154 20,933 20,774 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 4. Other operating income and costs continued (c) Key management compensation 2022 2021 2020 £m £m £m Short-term employee benefits 7 7 7 Compensation for loss of office — — 1 Post-employment benefits 1 1 1 Share-based payments 5 4 3 Total key management compensation 13 12 12 Auditors’ remuneration is presented below in accordance with the requirements of the Companies Act 2006 and the principal accountant fees and services disclosure requirements of Item 16C of Form 20-F: 2022 2021 2020 £m £m £m Audit fees payable to the Parent Company’s auditors and their associates in respect of: Audit of the Parent Company’s individual and consolidated financial statements 1 2.7 2.5 1.9 The auditing of accounts of any associate of the Company 8.9 8.1 8.7 Other services supplied 2 7.3 6.4 6.3 18.9 17.0 16.9 Total other services 3 All other fees: Other assurance services 4 0.9 0.8 0.6 Other non-audit services not covered above 5 0.1 2.0 0.5 1.0 2.8 1.1 Total auditors’ remuneration 19.9 19.8 18.0 1. Audit fees in each year represent fees for the audit of the Company’s financial statements and regulatory reporting for the years ended 31 March 2022, 2021 and 2020. 2. Other services supplied represent fees payable for services in relation to other statutory filings or engagements that are required to be carried out by the auditors. In particular, this includes fees for reports under section 404 of the US Public Company Accounting Reform and Investor Protection Act of 2002 (Sarbanes-Oxley), audit reports on regulatory returns and the review of interim financial statements for the six-month periods ended 30 September 2021, 2020 and 2019 respectively. 3. There were no tax compliance or tax advisory fees and no audit-related fees as described in Item 16C(b) of Form 20-F. 4. In all years, principally relates to assurance services provided in relation to comfort letters for debt issuances and, in 2021, also includes amounts related to capacity market auction monitoring services. 5. For 2021, includes the class 1 Circular in respect of the acquisition of WPD announced on 18 March 2021. In 2020, other assurance services include auction monitor work on Contracts for Difference, a review of controls over our data on New York customers and IT project assurance.

Exceptional items and remeasu_2

Exceptional items and remeasurements (Tables)	12 Months Ended
	Mar. 31, 2022
Exceptional Items And Remeasurements [Abstract]
Schedule of exceptional items and remeasurements from continuing operations	Exceptional items and remeasurements from continuing operations 2022 2021 1 2020 1 £m £m £m Included within operating profit Exceptional items: Release of St William Homes LLP deferred income 189 — — Net gain on disposal of St William Homes LLP 228 — — New operating model implementation costs and cost efficiency programme (66) (50) — Transaction and separation costs (223) (24) — Environmental insurance recovery 38 — — Changes in environmental provisions — 14 (400) 166 (60) (400) Remeasurements – commodity contract derivatives 392 34 (125) 558 (26) (525) 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. As disclosed in note 8, the Group also presents an adjusted earnings per share measure that is calculated before exceptional items and remeasurements. This measure is presented after tax and therefore details of tax exceptional items and the tax effect of exceptional items and remeasurements are also provided in this note. 2022 2021 1 2020 1 £m £m £m Included within finance income and costs Remeasurements: Net gains/(losses) on financing derivatives 74 47 (21) Net (losses)/gains on financial assets at fair value through profit and loss (15) 23 (16) 59 70 (37) Included within share of post-tax results of joint ventures and associates Remeasurements: Remeasurements – net losses on financial instruments (56) (8) (1) Total included within profit/(loss) before tax 561 36 (563) Included within tax Exceptional items – movements arising on items not included in profit before tax: Deferred tax charge arising as a result of UK tax rate change (458) — (148) Tax on exceptional items (28) 8 103 Tax on remeasurements (103) (34) 37 (589) (26) (8) Total exceptional items and remeasurements after tax (28) 10 (571) Analysis of total exceptional items and remeasurements after tax Exceptional items after tax (320) (52) (445) Remeasurements after tax 292 62 (126) Total exceptional items and remeasurements after tax (28) 10 (571)

Finance income and costs (Table

Finance income and costs (Tables)	12 Months Ended
	Mar. 31, 2022
Analysis of income and expense [abstract]
Schedule of finance income and costs	Finance income and costs remeasurements include unrealised gains and losses on certain assets and liabilities now treated at FVTPL. The interest income, dividends and interest expense on these items are included in finance income and finance costs before remeasurements respectively. 2022 2021 1 2020 1 Notes £m £m £m Finance income Interest income on financial instruments: Bank deposits and other financial assets 32 33 48 Dividends received on equities held at fair value through other comprehensive income (FVOCI) 3 2 2 Other income 30 — 20 65 35 70 Finance costs Net interest on pensions and other post-retirement benefit obligations 25 — (51) (34) Interest expense on financial liabilities held at amortised cost: Bank loans and overdrafts (216) (53) (46) Other borrowings² (961) (741) (846) Interest on derivatives (59) (47) (92) Unwinding of discount on provisions 26 (73) (77) (75) Other interest 11 (51) (8) Less: interest capitalised³ 152 120 102 (1,146) (900) (999) Remeasurements – Finance income Net gains/(losses) on FVTPL financial assets (15) 23 (16) (15) 23 (16) Remeasurements – Finance costs Net gains/(losses) on financing derivatives 4 : Derivatives designated as hedges for hedge accounting 45 30 (14) Derivatives not designated as hedges for hedge accounting 29 17 (7) 74 47 (21) Total remeasurements – Finance income and costs 59 70 (37) Finance income 50 58 54 Finance costs 5 (1,072) (853) (1,020) Net finance costs from continuing operations (1,022) (795) (966) 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 2. Includes interest expense on lease liabilities (see note 13 for details). 3. Interest on funding attributable to assets in the course of construction in the current year was capitalised at a rate of 3.2% (2021: 3.1%; 2020: 3.6%). In the UK, capitalised interest qualifies for a current year tax deduction with tax relief claimed of £16 million (2021: £11 million; 2020: £15 million). In the US, capitalised interest is added to the cost of property, plant and equipment and qualifies for tax depreciation allowances. 4. Includes a net foreign exchange gain on borrowing activities of £110 million (2021: £73 million gain; 2020: £114 million gain) offset by foreign exchange losses and gains on financing derivatives measured at fair value.

Tax (Tables)

Tax (Tables)	12 Months Ended
	Mar. 31, 2022
Income Taxes [Abstract]
Disclosure of major components of tax expense (income)	The tax charge for the year can be analysed as follows: 2022 2021 1 2020 1 £m £m £m Current tax: UK corporation tax at 19% (2021: 19%; 2020: 19%) 255 157 132 UK corporation tax adjustment in respect of prior years (9) 15 5 246 172 137 Overseas corporation tax 6 3 (2) Overseas corporation tax adjustment in respect of prior years (26) (15) (41) (20) (12) (43) Total current tax from continuing operations 226 160 94 Deferred tax: UK deferred tax 605 39 207 UK deferred tax adjustment in respect of prior years (5) (20) (4) 600 19 203 Overseas deferred tax 425 174 64 Overseas deferred tax adjustment in respect of prior years 7 7 9 432 181 73 Total deferred tax from continuing operations 1,032 200 276 Total tax charge from continuing operations 1,258 360 370
Disclosure of tax charged/(credited) to the consolidated statement of comprehensive income and equity	Tax charged/(credited) to the consolidated statement of comprehensive income and equity 2022 2021 1 2020 1 £m £m £m Current tax: Cash flow hedges, cost of hedging and own credit reserve — — — Deferred tax: Investments at fair value through other comprehensive income — 12 (1) Cash flow hedges, cost of hedging and own credit reserve (12) 6 (38) Remeasurements of pension assets and post-retirement benefit obligations 493 462 (226) Share-based payments (4) 1 (2) 477 481 (267) Total tax recognised in the statements of comprehensive income from continuing operations 481 480 (265) Total tax relating to share-based payments recognised directly in equity from continuing operations (4) 1 (2) 477 481 (267)
Disclosure of reconciliation of accounting profit multiplied by applicable tax rates and average effective tax rate	The tax charge for the year, for the continuing business, is higher (2021: higher tax charge; 2020: lower tax charge) than the standard rate of corporation tax in the UK of 19% (2021: 19%; 2020: 19%): 2022 2021 1 2020 1 £m £m £m Profit before tax from continuing operations Before exceptional items and remeasurements 2,880 1,628 1,963 Exceptional items and remeasurements 561 36 (563) Profit before tax from continuing operations 3,441 1,664 1,400 Profit before tax from continuing operations multiplied by UK corporation tax rate of 19% (2021: 19%; 2020: 19%) 654 316 266 Effect of: Adjustments in respect of prior years² (33) (12) (31) Expenses not deductible for tax purposes 47 29 24 Non-taxable income³ (49) (7) (18) Adjustment in respect of foreign tax rates⁴ 170 42 18 Deferred tax impact of change in UK tax rate 501 — 148 Adjustment in respect of post-tax profits of joint ventures and associates included within profit before tax (17) (12) (17) Other 5 (15) 4 (20) Total tax charge from continuing operations 1,258 360 370 % % % Effective tax rate – continuing operations 36.6 21.6 26.4 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. 2. The prior year adjustments are primarily due to agreement of prior period tax returns. 3. Includes tax on chargeable disposals after the offset of capital losses and tax on the profits deferred to the following accounting period. 4. Includes remeasurement of US closing State deferred tax balances as a result of expected increase in the blended State tax rate following the disposal of NECO. 5. Other primarily comprises the movement in the deferred tax asset on previously unrecognised capital losses, claims for land remediation relief and impact of fair value movements on capitalised hedging.
Disclosure of temporary difference, unused tax losses and unused tax credits	The following are the major deferred tax assets and liabilities recognised, and the movements thereon, during the current and prior reporting periods: Regulatory licences Accelerated Share- Pensions Financial Other net differences 1 £m Total Deferred tax liabilities/(assets) At 1 April 2020 — 6,562 (48) (360) (55) (1,653) 4,446 Exchange adjustments and other 2 — (501) 4 51 4 174 (268) Charged/(credited) to income statement — 373 — (12) 1 (147) 215 Charged to other comprehensive income and equity — — 2 414 6 — 422 At 1 April 2021 — 6,434 (42) 93 (44) (1,626) 4,815 Exchange adjustments and other 2 — 247 (1) 1 1 (85) 163 Charged/(credited) to income statement — 1,050 26 118 153 (117) 1,230 Charged/(credited) to other comprehensive income and equity — — (6) 587 (10) — 571 Reclassification to held for sale (note 10) — (643) 5 (166) 2 (1) (803) Acquisition of WPD (note 37) 429 622 — 142 (403) (1) 789 At 31 March 2022 429 7,710 (18) 775 (301) (1,830) 6,765 1. The deferred tax asset of £1,830 million as at 31 March 2022 (2021: £1,626 million) in respect of other net temporary differences primarily relates to net operating losses of £428 million (2021: £455 million), US environmental provisions of £511 million (2021: £453 million) and US bad debt provision of £201 million (2021: £184 million). 2. Exchange adjustments and other primarily comprises foreign exchange arising on translation of the US dollar deferred tax balances. 2022 2021 £m £m Capital losses 2,363 1,620 Non-trade deficits 1 1 Trading losses 7 7

Earnings per share (EPS) (Table

Earnings per share (EPS) (Tables)	12 Months Ended
	Mar. 31, 2022
Earnings per share [abstract]
Schedule of earnings per share	(a) Basic EPS Earnings EPS Earnings EPS Earnings EPS 2022 2022 2021 1 2021 1 2020 1 2020 1 £m pence £m pence £m pence Adjusted earnings from continuing operations 2,210 61.4 1,293 36.7 1,600 46.2 Exceptional items and remeasurements after tax from continuing operations (see note 5) (28) (0.8) 10 0.3 (571) (16.5) Earnings from continuing operations 2,182 60.6 1,303 37.0 1,029 29.7 Adjusted earnings from discontinued operations (see note 10) 344 9.6 340 9.7 317 9.2 Exceptional items and remeasurements after tax from discontinued operations (173) (4.8) (3) (0.1) (82) (2.4) Earnings from discontinued operations 171 4.8 337 9.6 235 6.8 Total adjusted earnings 2,554 71.0 1,633 46.4 1,917 55.4 Total exceptional items and remeasurements after tax (including discontinued operations) (201) (5.6) 7 0.2 (653) (18.9) Total earnings 2,353 65.4 1,640 46.6 1,264 36.5 2022 2021 2020 millions millions millions Weighted average number of ordinary shares – basic 3,599 3,523 3,461 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. (b) Diluted EPS Earnings EPS Earnings EPS Earnings EPS 2022 2022 2021 1 2021 1 2020 1 2020 1 £m pence £m pence £m pence Adjusted earnings from continuing operations 2,210 61.1 1,293 36.5 1,600 46.0 Exceptional items and remeasurements after tax from continuing operations (see note 5) (28) (0.8) 10 0.3 (571) (16.4) Earnings from continuing operations 2,182 60.3 1,303 36.8 1,029 29.6 Adjusted earnings from discontinued operations 344 9.5 340 9.6 317 9.1 Exceptional items and remeasurements after tax from discontinued operations (see note 10) (173) (4.8) (3) (0.1) (82) (2.4) Earnings from discontinued operations 171 4.7 337 9.5 235 6.7 Total adjusted earnings 2,554 70.6 1,633 46.1 1,917 55.1 Total exceptional items and remeasurements after tax (including discontinued operations) (201) (5.6) 7 0.2 (653) (18.8) Total earnings 2,353 65.0 1,640 46.3 1,264 36.3 2022 2021 2020 millions millions millions Weighted average number of ordinary shares – diluted 3,616 3,540 3,478 1. Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information. (c) Reconciliation of basic to diluted average number of shares 2022 2021 2020 millions millions millions Weighted average number of ordinary shares – basic 3,599 3,523 3,461 Effect of dilutive potential ordinary shares – employee share plans 17 17 17 Weighted average number of ordinary shares – diluted 3,616 3,540 3,478

Dividends (Tables)

Dividends (Tables)	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Schedule of dividends to shareholders	Interim dividends are recognised when they become payable to the Company’s shareholders. Final dividends are recognised when they are approved by shareholders. 2022 2021 2020 Pence Cash Scrip dividend Pence per share Cash Scrip dividend £m Pence per share Cash Scrip dividend £m Interim dividend in respect of the current year 17.21 339 282 17.00 348 249 16.57 335 241 Final dividend in respect of the prior year 32.16 583 562 32.00 1,065 54 31.26 557 517 49.37 922 844 49.00 1,413 303 47.83 892 758

Assets held for sale and disc_2

Assets held for sale and discontinued operations (Tables)	12 Months Ended
	Mar. 31, 2022
Non-current Assets Held For Sale And Discontinued Operations [Abstract]
Schedule of held for sale and discontinued operations	The following assets and liabilities were classified as held for sale as at 31 March 2022: Total assets Total liabilities held for sale Net assets held for sale The Narragansett Electric Company 4,129 (1,658) 2,471 UK Gas Transmission 5,871 (5,530) 341 Net assets held for sale 10,000 (7,188) 2,812 Whilst all of the regulatory approvals are in place, the disposal of NECO was not finalised as at 31 March 2022 due to the appeal of one of these approvals by the Rhode Island Attorney General. The following assets and liabilities of NECO were classified as held for sale at 31 March 2022: £m Goodwill 590 Intangible assets 4 Property, plant and equipment 3,173 Trade and other receivables 251 Cash and cash equivalents 6 Other assets 105 Total assets held for sale 4,129 Borrowings (1,177) Pension liabilities (12) Other liabilities (469) Total liabilities held for sale (1,658) Net assets held for sale 2,471 £m Intangible assets 159 Property, plant and equipment 4,719 Trade and other receivables 215 Pension assets 664 Cash and cash equivalents 9 Financing derivatives 93 Other assets 12 Total assets held for sale 5,871 Borrowings (4,165) Deferred tax liabilities (803) Other liabilities (562) Total liabilities held for sale (5,530) Net assets held for sale 341 The summary income statements for UK Gas Transmission and Quadgas, together representing the discontinued operations of the Group, for the years ended 31 March 2022, 2021 and 2020 are as follows: 2022 2021 2020 £m £m £m Discontinued operations Revenue 1,362 1,114 1,180 Other operating costs (725) (620) (702) Operating profit 637 494 478 Finance income — — 6 Finance costs 1 (230) (75) (147) Profit before tax 407 419 337 Tax 2 (236) (82) (111) Profit after tax from discontinued operations 171 337 226 Gain on disposal — — 9 Total profit after tax from discontinued operations 171 337 235 1. Finance costs from discontinued operations include principal accretion of inflation linked liabilities in the UK Gas Transmission business of £158 million (2021: £38 million; 2020: £76 million). 2. Of the £236 million tax charge in the year ended 31 March 2022, £145 million relates to deferred tax due to the change in the UK corporation tax rate. The summary statement of comprehensive income for discontinued operations for the years ended 31 March 2022, 2021 and 2020 are as follows: 2022 2021 2020 £m £m £m Profit after tax from discontinued operations 171 337 235 Other comprehensive income/(loss) from discontinued operations Items from discontinued operations that will never be reclassified to profit or loss: Remeasurement gains/(losses) on pension assets and post-retirement benefit obligations 309 (250) 58 Net losses on financial liability designated at fair value through profit and loss attributable to changes in own credit risk (1) (11) (3) Net losses in respect of cash flow hedging of capital expenditure — (2) — Tax on items that will never be reclassified to profit or loss (94) 50 (20) Total gains/(losses) from discontinued operations that will never be reclassified to profit or loss 214 (213) 35 Items from discontinued operations that may be reclassified subsequently to profit or loss: Net gains/(losses) in respect of cash flow hedges 1 3 (1) Net (losses)/gains in respect of cost of hedging (4) (6) 2 Tax on items that may be reclassified subsequently to profit or loss — — 2 Total losses from discontinued operations that may be reclassified subsequently to profit or loss (3) (3) 3 Other comprehensive income/(loss) for the year, net of tax from discontinued operations 211 (216) 38 Total comprehensive income for the year from discontinued operations 382 121 273

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Mar. 31, 2022
Intangible Assets [Abstract]
Schedule of changes in intangible assets and goodwill	Total £m Net book value at 1 April 2020 5,712 Exchange adjustments (562) Reclassification to held for sale (note 10) (562) Net book value at 1 April 2021 4,588 Exchange adjustments 223 Acquisition of WPD (note 37) 4,721 Net book value at 31 March 2022 9,532
Intangible assets and goodwill allocated by operation	See below for a summary of which operations our goodwill and indefinite-lived intangibles are allocated to: 2022 CGU or group of CGUs £m Goodwill: National Grid Ventures Renewables 150 New England 1,510 New York 3,151 WPD 1 4,721 Total goodwill 9,532 Indefinite-lived intangibles (regulatory licences related to WPD): West Midlands 518 East Midlands 519 South Wales 257 South West 420 Total indefinite-lived intangibles 1,714 1. This is a combination of the West Midlands, East Midlands, South Wales and South West CGUs, reflecting the level at which the goodwill is monitored.

Other intangible assets (Tables

Other intangible assets (Tables)	12 Months Ended
	Mar. 31, 2022
Intangible Assets [Abstract]
Schedule of intangible assets	Amortisation periods for other intangible assets are: Years Software 3 to 10 Regulatory licences Indefinite Regulatory licences 1 £m Software £m Assets in the course of construction Total Cost at 1 April 2020 — 2,026 557 2,583 Exchange adjustments — (102) (43) (145) Additions — 7 414 421 Disposals — (47) (2) (49) Reclassifications 2 — 255 (240) 15 Reclassification to held for sale (note 10) — (19) — (19) Cost at 1 April 2021 — 2,120 686 2,806 Exchange adjustments — 69 11 80 Additions — 15 513 528 Acquisition of WPD (note 37) 1,714 49 — 1,763 Disposals — (7) — (7) Reclassifications 2 — 260 (302) (42) Reclassification to held for sale (note 10) — (431) (38) (469) Cost at 31 March 2022 1,714 2,075 870 4,659 Accumulated amortisation at 1 April 2020 — (1,288) — (1,288) Exchange adjustments — 61 — 61 Amortisation charge for the year — (196) — (196) Accumulated amortisation of disposals — 44 — 44 Reclassification to held for sale (note 10) — 16 — 16 Accumulated amortisation at 1 April 2021 — (1,363) — (1,363) Exchange adjustments — (33) — (33) Amortisation charge for the year — (297) — (297) Impairment³ — — (10) (10) Accumulated amortisation of disposals — 7 — 7 Reclassification to held for sale (note 10) — 309 — 309 Accumulated amortisation at 31 March 2022 — (1,377) (10) (1,387) Net book value at 31 March 2022⁴ 1,714 698 860 3,272 Net book value at 31 March 2021 — 757 686 1,443 1. Relates to the licence intangibles acquired as part of the acquisition of WPD (see note 37). The Group assesses its indefinite-life intangible assets for impairment annually (see note 11). 2. Reclassifications includes amounts transferred to property, plant and equipment (see note 13). 3. Depreciation of assets in the course of construction relates to impairment provision adjustments recognised in the year. 4. The Group has capitalised £366 million (2021: £298 million) in relation to the Gas Business Enablement system in the US, of which £152 million (2021: £82 million) is in service and is being amortised over 10 years, with the remainder included within assets in the course of construction. A further £103 million (2021: £nil) in relation to our new UK general ledger system was reclassified from assets in the course of construction to software assets in the period to 31 March 2022, and is now amortised over 10 years.

Property, plant and equipment (

Property, plant and equipment (Tables)	12 Months Ended
	Mar. 31, 2022
Property, plant and equipment [abstract]
Schedule of property, plant and equipment	Land and buildings £m Plant and machinery £m Assets Motor vehicles and office equipment £m Total £m Cost at 1 April 2020 3,897 59,609 4,771 1,036 69,313 Exchange adjustments (213) (3,308) (130) (73) (3,724) Additions 89 328 4,023 70 4,510 Disposals (6) (344) (26) (48) (424) Reclassifications¹ 96 3,007 (3,243) 77 (63) Reclassification to held for sale (note 10) (111) (3,231) (174) (44) (3,560) Cost at 1 April 2021 3,752 56,061 5,221 1,018 66,052 Exchange adjustments 97 1,627 111 37 1,872 Additions 22 926 4,843 129 5,920 Acquisition of WPD (note 37) 200 9,512 185 154 10,051 Disposals (165) (367) — (88) (620) Reclassifications¹ 62 4,063 (4,133) 89 81 Reclassification to held for sale (note 10) (309) (8,800) (640) (267) (10,016) Cost at 31 March 2022 3,659 63,022 5,587 1,072 73,340 Accumulated depreciation at 1 April 2020 (847) (18,042) — (662) (19,551) Exchange adjustments 37 698 — 46 781 Depreciation charge for the year (90) (1,270) — (116) (1,476) Disposals — 339 — 48 387 Reclassifications¹ 2 (5) — 6 3 Reclassification to held for sale (note 10) 22 798 — 27 847 Accumulated depreciation at 1 April 2021 (876) (17,482) — (651) (19,009) Exchange adjustments (20) (351) — (23) (394) Depreciation charge for the year² (114) (1,300) (48) (167) (1,629) Disposals 29 311 — 88 428 Reclassifications¹ 15 (40) (18) 2 (41) Reclassification to held for sale (note 10) 193 4,421 6 217 4,837 Accumulated depreciation at 31 March 2022 (773) (14,441) (60) (534) (15,808) Net book value at 31 March 2022 2,886 48,581 5,527 538 57,532 Net book value at 31 March 2021 2,876 38,579 5,221 367 47,043 1. Represents amounts transferred between categories, (to)/from other intangible assets (see note 12), from inventories and reclassifications between cost and accumulated depreciation. 2. Depreciation of assets in the course of construction relates to impairment provision adjustments recognised in the year. 13. Property, plant and equipment continued (a) Analysis of property, plant and equipment continued 2022 2021 £m £m Information in relation to property, plant and equipment Capitalised interest included within cost 2,114 2,233 Contributions to cost of property, plant and equipment included within: Trade and other payables 137 138 Non-current liabilities 421 400 Contract liabilities – current 130 66 Contract liabilities – non-current 1,342 1,094 Years UK US Weighted average remaining UEL¹ Freehold and leasehold buildings up to 60 up to 100 41 Plant and machinery: Electricity transmission plant and wires up to 100 45 to 80 31 Electricity distribution plant 3 to 99 35 to 85 45 Electricity generation plant n/a 20 to 93 12 Interconnector plant and other 5 to 60 5 to 50 32 Gas plant – mains, services and regulating equipment n/a 47 to 80 55 Gas plant – storage 5 to 40 12 to 65 12 Gas plant – meters 7 to 30 14 to 40 24 Motor vehicles and office equipment up to 30 up to 26 5 1. Excluded from the above table are depreciation periods in respect of items of property, plant and equipment which are classified as held for sale as at 31 March 2022. Increase in depreciation expense for the year ended 31 March 2022 Increase in depreciation expense for the year ended 31 March 2021 1 New York New England New York New England UELs limited to 2050 140 40 125 35 UELs limited to 2060 67 15 57 13 UELs limited to 2070 31 1 26 2
Schedule of information about right-of-use assets	The table below shows the movements in the net book value of right-of-use assets included within property, plant and equipment at 31 March 2022 and 31 March 2021, split by category. The associated lease liabilities are disclosed in note 21. Land and Plant and Assets Motor Total Net book value at 1 April 2020 364 95 — 225 684 Exchange adjustments (30) (4) — (22) (56) Additions 60 6 — 64 130 Reclassifications — — — (15) (15) Depreciation charge for the year (29) (16) — (68) (113) Net book value at 31 March 2021 365 81 — 184 630 Exchange adjustments 10 1 — 10 21 Additions 14 2 — 88 104 Acquisition of WPD (note 37) 7 2 — — 9 Reclassification to held for sale (note 10) (7) — — (4) (11) Modifications of leases¹ (122) — — — (122) Disposals (2) — — (1) (3) Depreciation charge for the year (40) (16) — (67) (123) Net book value at 31 March 2022 225 70 — 210 505 The following balances have been included in the income statement for the years ended 31 March 2022 and 31 March 2021 in respect of right-of-use assets: 2022 2021 £m £m Included within net finance income and costs: Interest expense on lease liabilities (18) (21) Included within revenue: Lease income¹ 385 390 Included within operating expenses: Expense relating to short-term and low-value leases (14) (13)

Other non-current assets (Table

Other non-current assets (Tables)	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Schedule of other non-current assets	2022 2021 £m £m Other receivables 110 45 Non-current tax assets 6 6 Prepayments — 5 Accrued income¹ 187 237 303 293

Financial and other investmen_2

Financial and other investments (Tables)	12 Months Ended
	Mar. 31, 2022
Disclosure of financial assets [abstract]
Schedule of financial assets	2022 2021 £m £m Non-current FVOCI debt and other investments 413 416 FVOCI equity investments¹ — 99 FVTPL investments 417 240 830 755 Current FVTPL investments 2,292 1,768 Financial assets at amortised cost 853 574 3,145 2,342 3,975 3,097 Financial and other investments include the following: Investments in short-term money market funds 1,936 1,412 Investments held by National Grid Partners 309 136 Investments in Sunrun 109 103 Balances that are restricted or not readily used in operations: Collateral 2 806 540 Insurance company and non-qualified plan investments 534 589 Cash surrender value of life insurance policies 234 283 Other investments 47 34 3,975 3,097 1. In the year ended 31 March 2022, the Group sold its equity investments which were previously held in relation to non-qualified pension plans in the US. 2. The collateral balance includes £802 million (2021: £480 million) of collateral placed with counterparties with whom we have entered into a credit support annex to the International Swaps and Derivatives Association (ISDA) Master Agreement and £4 million (2021: £18 million) of restricted amounts allocated for specific projects within the National Grid Electricity System Operator. In the year ended 31 March 2021, £42 million of the balance included collateral paid by operating companies as security deposits. In the current year this collateral has been replaced with letters of credit as permitted under the Connection and Use of System Code.

Investments in joint ventures_2

Investments in joint ventures and associates (Tables)	12 Months Ended
	Mar. 31, 2022
Interests In Other Entities [Abstract]
Disclosure of joint ventures	2022 2021 Associates Joint Total Associates £m Joint ventures £m Total £m Share of net assets at 1 April 229 638 867 341 654 995 Exchange adjustments 6 19 25 (22) (36) (58) Additions 17 469 486 6 75 81 Share of post-tax results for the year 43 49 92 30 28 58 Share of other comprehensive income of associates, net of tax 1 — 1 1 — 1 Dividends received (35) (123) (158) (31) (49) (80) Disposals — (50) (50) — — — Other movements¹ 16 (41) (25) (96) (34) (130) Share of net assets at 31 March 277 961 1,238 229 638 867 1. Other movements relate to tax liabilities for US and certain UK associates and joint ventures which are borne by the Group and the elimination of profits arising from sales to the Group’s share of joint ventures. Within associates, the other movements in the year ended 31 March 2021 primarily relates to the reclassification of the Group’s investment in Sunrun from an investment in an associate to financial investments. The following table describes the Group’s material joint ventures and associates at 31 March 2022: Joint venture % stake BritNed Development Limited 1 50 % BritNed is a joint venture with the Dutch transmission system operator, TenneT, and operates the subsea electricity link between Great Britain and the Netherlands, commissioned in 2011. Nemo Link Limited 1 50 % Nemo is a joint venture with the Belgian transmission operator, Elia, and is a subsea electricity interconnector between Great Britain and Belgium, which became operational on 31 January 2019. Emerald Energy Venture LLC 51 % Emerald is a joint venture with Washington State Investment Board and builds and operates wind and solar assets. Emerald was acquired on 11 July 2019. Bight Wind Holdings LLC 27.3 % Bight Wind is a joint venture with RWE Renewables. Following the successful win at auction of six seabed leases in northeastern US on 25 February 2022, Bight Wind will commence the development of an offshore wind project which will play a key role in supplying clean energy to customers in New York. At 31 March 2022, the Group has an amount payable to Bight Wind of £223 million in respect of a capital call to the Group which is payable in April 2022. The assets, liabilities and results of Bight Wind will become material to the Group upon recognition of the seabed lease in the year ending 31 March 2023. Material associate % stake Millennium Pipeline Company LLC 26.25 % Millennium Pipeline Company LLC is an associate that owns a natural gas pipeline from southern New York to the Lower Hudson Valley. 1. BritNed and Nemo have reporting periods ending on 31 December with monthly management reporting information provided to National Grid. Summarised financial information as at 31 March, together with the carrying amount of material investments, is as follows: BritNed Development Nemo Link Limited Emerald Energy Millennium Pipeline Company LLC 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Statement of financial position Non-current assets 390 409 515 536 1,070 559 800 795 Cash and cash equivalents 77 47 7 31 134 112 33 27 All other current assets 10 24 7 8 8 12 29 24 Non-current liabilities (52) (50) (34) (30) (182) (182) (237) (256) Non-current financial liabilities (29) (31) — — (310) (104) — — Current liabilities (15) (22) (33) (19) (66) (25) (45) (38) Current financial liabilities — — — — (23) (2) — — Net assets 381 377 462 526 631 370 580 552 Group’s ownership interest 191 189 231 263 322 189 152 145 Group adjustment: elimination — — — — (49) (23) — — Carrying amount of the Group’s investment 191 189 231 263 273 166 152 145 BritNed Development Nemo Link Limited Emerald Energy Millennium Pipeline Company LLC 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Income statement Revenue 131 72 148 66 25 28 200 199 Depreciation and amortisation (15) (15) (23) (24) (17) (14) (43) (43) Other costs (9) (15) (6) (6) (145) (22) (20) (21) Operating profit/(loss) 107 42 119 36 (137) (8) 137 135 Net interest expense (2) (1) (1) — (5) — (21) (18) Profit/(loss) before tax 105 41 118 36 (142) (8) 116 117 Income tax expense (20) (11) (22) (14) — — — — Profit/(loss) for the year 85 30 96 22 (142) (8) 116 117 Group’s share of profit/(loss) 43 15 48 11 (72) (4) 30 31 Group adjustment: tax credit/(charge) — — — — 19 1 (8) (9) Group’s share of post-tax results for the year 43 15 48 11 (53) (3) 22 22
Disclosure of associates	2022 2021 Associates Joint Total Associates £m Joint ventures £m Total £m Share of net assets at 1 April 229 638 867 341 654 995 Exchange adjustments 6 19 25 (22) (36) (58) Additions 17 469 486 6 75 81 Share of post-tax results for the year 43 49 92 30 28 58 Share of other comprehensive income of associates, net of tax 1 — 1 1 — 1 Dividends received (35) (123) (158) (31) (49) (80) Disposals — (50) (50) — — — Other movements¹ 16 (41) (25) (96) (34) (130) Share of net assets at 31 March 277 961 1,238 229 638 867 1. Other movements relate to tax liabilities for US and certain UK associates and joint ventures which are borne by the Group and the elimination of profits arising from sales to the Group’s share of joint ventures. Within associates, the other movements in the year ended 31 March 2021 primarily relates to the reclassification of the Group’s investment in Sunrun from an investment in an associate to financial investments. The following table describes the Group’s material joint ventures and associates at 31 March 2022: Joint venture % stake BritNed Development Limited 1 50 % BritNed is a joint venture with the Dutch transmission system operator, TenneT, and operates the subsea electricity link between Great Britain and the Netherlands, commissioned in 2011. Nemo Link Limited 1 50 % Nemo is a joint venture with the Belgian transmission operator, Elia, and is a subsea electricity interconnector between Great Britain and Belgium, which became operational on 31 January 2019. Emerald Energy Venture LLC 51 % Emerald is a joint venture with Washington State Investment Board and builds and operates wind and solar assets. Emerald was acquired on 11 July 2019. Bight Wind Holdings LLC 27.3 % Bight Wind is a joint venture with RWE Renewables. Following the successful win at auction of six seabed leases in northeastern US on 25 February 2022, Bight Wind will commence the development of an offshore wind project which will play a key role in supplying clean energy to customers in New York. At 31 March 2022, the Group has an amount payable to Bight Wind of £223 million in respect of a capital call to the Group which is payable in April 2022. The assets, liabilities and results of Bight Wind will become material to the Group upon recognition of the seabed lease in the year ending 31 March 2023. Material associate % stake Millennium Pipeline Company LLC 26.25 % Millennium Pipeline Company LLC is an associate that owns a natural gas pipeline from southern New York to the Lower Hudson Valley. 1. BritNed and Nemo have reporting periods ending on 31 December with monthly management reporting information provided to National Grid. Summarised financial information as at 31 March, together with the carrying amount of material investments, is as follows: BritNed Development Nemo Link Limited Emerald Energy Millennium Pipeline Company LLC 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Statement of financial position Non-current assets 390 409 515 536 1,070 559 800 795 Cash and cash equivalents 77 47 7 31 134 112 33 27 All other current assets 10 24 7 8 8 12 29 24 Non-current liabilities (52) (50) (34) (30) (182) (182) (237) (256) Non-current financial liabilities (29) (31) — — (310) (104) — — Current liabilities (15) (22) (33) (19) (66) (25) (45) (38) Current financial liabilities — — — — (23) (2) — — Net assets 381 377 462 526 631 370 580 552 Group’s ownership interest 191 189 231 263 322 189 152 145 Group adjustment: elimination — — — — (49) (23) — — Carrying amount of the Group’s investment 191 189 231 263 273 166 152 145 BritNed Development Nemo Link Limited Emerald Energy Millennium Pipeline Company LLC 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Income statement Revenue 131 72 148 66 25 28 200 199 Depreciation and amortisation (15) (15) (23) (24) (17) (14) (43) (43) Other costs (9) (15) (6) (6) (145) (22) (20) (21) Operating profit/(loss) 107 42 119 36 (137) (8) 137 135 Net interest expense (2) (1) (1) — (5) — (21) (18) Profit/(loss) before tax 105 41 118 36 (142) (8) 116 117 Income tax expense (20) (11) (22) (14) — — — — Profit/(loss) for the year 85 30 96 22 (142) (8) 116 117 Group’s share of profit/(loss) 43 15 48 11 (72) (4) 30 31 Group adjustment: tax credit/(charge) — — — — 19 1 (8) (9) Group’s share of post-tax results for the year 43 15 48 11 (53) (3) 22 22

Derivative financial instrume_2

Derivative financial instruments (Tables)	12 Months Ended
	Mar. 31, 2022
Financial Instruments [Abstract]
Disclosure of detailed information about derivative financial instruments	The fair values of derivatives by category are as follows: 2022 2021 Assets Liabilities Total £m Assets £m Liabilities £m Total £m Current 282 (144) 138 457 (145) 312 Non-current 305 (869) (564) 542 (754) (212) 587 (1,013) (426) 999 (899) 100 Financing derivatives 298 (991) (693) 942 (767) 175 Commodity contract derivatives 289 (22) 267 57 (132) (75) 587 (1,013) (426) 999 (899) 100 The fair values of financing derivatives by type are as follows: 2022 2021 Assets Liabilities Total £m Assets £m Liabilities £m Total £m Interest rate swaps 89 (97) (8) 325 (159) 166 Cross-currency interest rate swaps 174 (642) (468) 601 (351) 250 Foreign exchange forward contracts¹ 35 (65) (30) 16 (74) (58) Inflation-linked swaps — (187) (187) — (183) (183) 298 (991) (693) 942 (767) 175 The notional contract amounts of financing derivatives by type are as follows: 2022 2021 £m £m Interest rate swaps (1,607) (2,259) Cross-currency interest rate swaps (10,397) (8,389) Foreign exchange forward contracts (6,371) (4,651) Inflation-linked swaps (500) (500) (18,875) (15,799) The fair values of commodity contract derivatives by type are as follows: 2022 2021 Assets Liabilities Total Assets Liabilities £m Total £m Commodity purchase contracts accounted for as derivative contracts Forward purchases of gas 11 (6) 5 44 (94) (50) Derivative financial instruments linked to commodity prices Electricity capacity 1 — 1 2 — 2 Electricity swaps 208 (10) 198 10 (33) (23) Electricity options 5 — 5 — (1) (1) Gas swaps 29 (6) 23 1 (3) (2) Gas options 35 — 35 — (1) (1) 289 (22) 267 57 (132) (75) The notional quantities of commodity contract derivatives by type are as follows: 2022 2021 Forward purchases of gas 1 28m Dth 36m Dth Electricity swaps 13,458 GWh 12,321 GWh Gas swaps 39m Dth 47m Dth Gas options 59m Dth 40m Dth
Disclosure of maturity analysis for derivative financial liabilities	The maturity profile of financing derivatives is as follows: 2022 2021 Assets Liabilities Total Assets £m Liabilities £m Total Current Less than 1 year 34 (136) (102) 428 (70) 358 34 (136) (102) 428 (70) 358 Non-current In 1 to 2 years 6 (29) (23) 10 (14) (4) In 2 to 3 years 28 (39) (11) 24 (12) 12 In 3 to 4 years — (26) (26) 62 (80) (18) In 4 to 5 years 12 (16) (4) 4 (42) (38) More than 5 years 218 (745) (527) 414 (549) (135) 264 (855) (591) 514 (697) (183) 298 (991) (693) 942 (767) 175 The maturity profile of commodity contract derivatives is as follows: 2022 2021 Assets Liabilities Total Assets £m Liabilities £m Total £m Current Less than one year 248 (8) 240 29 (75) (46) 248 (8) 240 29 (75) (46) Non-current In 1 to 2 years 34 (6) 28 7 (24) (17) In 2 to 3 years 5 (5) — 7 (16) (9) In 3 to 4 years 2 (2) — 7 (7) — In 4 to 5 years — (1) (1) 6 (5) 1 More than 5 years — — — 1 (5) (4) 41 (14) 27 28 (57) (29) 289 (22) 267 57 (132) (75)

Inventories and current intan_2

Inventories and current intangible assets (Tables)	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Schedule of inventories and current intangible assets	2022 2021 £m £m Fuel stocks 96 94 Raw materials and consumables 297 253 Current intangible assets – emission allowances 118 92 511 439

Trade and other receivables (Ta

Trade and other receivables (Tables)	12 Months Ended
	Mar. 31, 2022
Trade and other receivables [abstract]
Schedule of trade and other receivables	Trade and other receivables are initially recognised at fair value and subsequently measured at amortised cost, less any appropriate allowances for estimated irrecoverable amounts. 2022 2021 £m £m Trade receivables 2,661 2,152 Accrued income 1,110 886 Provision for impairment of receivables and accrued income (741) (672) Trade receivables and accrued income, net 3,030 2,366 Prepayments 429 387 Contract assets 33 13 Other receivables 223 153 3,715 2,919
Schedule of reconciliation of changes in allowance account for credit losses	A provision for credit losses is recognised at an amount equal to the expected credit losses that will arise over the lifetime of the trade receivables and accrued income. 2022 2021 £m £m At 1 April 672 512 Exchange adjustments 31 (57) Charge for the year, net of recoveries 167 326 Uncollectible amounts written off (124) (59) Reclassification to held for sale (note 10) (5) (50) At 31 March 741 672
Schedule of receivables by geographical area	The trade receivables balance, accrued income balance and provisions balance split by geography are as follows: As at 31 March 2022 As at 31 March 2021 UK US Total UK US Total £m £m £m £m £m £m Trade receivables 352 2,309 2,661 227 1,925 2,152 Accrued income 715 395 1,110 547 339 886 Provision for impairment of receivables and accrued income (43) (698) (741) (23) (649) (672) 1,024 2,006 3,030 751 1,615 2,366
Schedule of average expected loss rates and balances	The average expected loss rates and gross balances for the retail customer receivables in our US operations are set out below: 2022 2021 % £m % £m Accrued income 5 382 7 322 0 – 30 days past due 5 731 7 580 30 – 60 days past due 20 213 24 155 60 – 90 days past due 32 123 36 108 3 – 6 months past due 41 161 52 140 6 – 12 months past due 56 177 66 180 Over 12 months past due 71 456 71 367 2,243 1,852

Cash and cash equivalents (Tabl

Cash and cash equivalents (Tables)	12 Months Ended
	Mar. 31, 2022
Cash and cash equivalents [abstract]
Schedule of cash and cash equivalents	2022 2021 £m £m Cash at bank 204 117 Short-term deposits — 40 Cash and cash equivalents 204 157

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Mar. 31, 2022
Disclosure of detailed information about borrowings [abstract]
Schedule of borrowings	2022 2021 £m £m Current Bank loans¹ 8,976 1,022 Bonds² 1,735 1,987 Commercial paper 1,303 628 Lease liabilities 107 99 Other loans — 1 12,121 3,737 Non-current Bank loans 2,211 2,532 Bonds 30,682 24,209 Lease liabilities 451 586 Other loans — 156 33,344 27,483 Total borrowings 45,465 31,220 1. Current bank loans include £8,179 million of borrowings under the bridge facility relating to the acquisition of WPD (31 March 2021: undrawn). The bridge facility allows for the extension of the maturity date up to September 2023 but includes a requirement that the proceeds of the planned sales of NECO and the UK Gas Transmission business are applied to repay the facility. As these are expected to completed within one year the position has been classified as current. 2. Includes a liability held at fair value through profit and loss of £nil (2021: £682 million). Total borrowings are repayable as follows: 2022 2021 £m £m Less than 1 year 12,121 3,737 In 1 to 2 years 1,410 1,745 In 2 to 3 years 2,544 889 In 3 to 4 years 2,580 2,206 In 4 to 5 years 2,493 1,833 More than 5 years: By instalments 869 927 Other than by instalments 23,448 19,883 45,465 31,220
Schedule of lease obligations	2022 2021 £m £m Gross lease liabilities are repayable as follows: Less than 1 year 132 114 1 to 5 years 282 321 More than 5 years 259 464 673 899 Less: finance charges allocated to future periods (115) (214) 558 685 The present value of lease liabilities are as follows: Less than 1 year 107 99 1 to 5 years 247 267 More than 5 years 204 319 558 685

Trade and other payables (Table

Trade and other payables (Tables)	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Schedule of trade and other payables	2022 2021 £m £m Trade payables 3,113 2,165 Deferred payables 487 154 Customer contributions¹ 137 138 Social security and other taxes 278 140 Contingent consideration 34 39 Other payables 866 881 4,915 3,517 1. Relates to amounts received from government-related entities for connecting to our networks, where we have obligations remaining under the contract.

Contract liabilities (Tables)

Contract liabilities (Tables)	12 Months Ended
	Mar. 31, 2022
Contract liabilities [abstract]
Summary of contract liabilities	2022 2021 £m £m Current 130 66 Non-current 1,342 1,094 1,472 1,160
Explanation of significant changes in contract assets and contract liabilities	Significant changes in the contract liabilities balances during the period are as follows: 2022 2021 £m £m As at 1 April 1,160 1,158 Exchange adjustments 29 (65) Revenue recognised that was included in the contract liability balance at the beginning of the period (53) (96) Increases due to cash received, excluding amounts recognised as revenue during the period 510 262 Reclassification to held for sale (note 10) (174) (99) At 31 March 1,472 1,160

Other non-current liabilities (

Other non-current liabilities (Tables)	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Schedule of other non-current liabilities	Other non-current liabilities are initially recognised at fair value and subsequently measured at amortised cost, with the exception of contingent consideration, which is subsequently measured at fair value. 2022 2021 £m £m Deferred income¹ 41 78 Customer contributions² 421 400 Contingent consideration 7 18 Other payables 336 347 805 843 1. In the year ended 31 March 2021, principally the deferral of profits relating to the sale of property to St William Homes LLP, which were expected to be recognised in future years. In the year ended 31 March 2022, the Group disposed of its interests in St William Homes LLP, resulting in a release of previously deferred profits (see note 16). 2. Relates to amounts received from government-related entities for connecting to our networks, where we have obligations remaining under the contract.

Pensions and other post-retir_2

Pensions and other post-retirement benefits (Tables)	12 Months Ended
	Mar. 31, 2022
Employee Benefits [Abstract]
Disclosure of actuarial assumptions	The Company has applied the following financial assumptions in assessing DB liabilities: UK pensions US pensions US other post-retirement benefits 2022 2021 2020 2022 2021 2020 2022 2021 2020 % % % % % % % % % Discount rate – past service 2.78 2.00 2.35 3.65 3.25 3.30 3.65 3.25 3.30 Discount rate – future service 2.85 2.15 2.35 3.65 3.25 3.30 3.65 3.25 3.30 Rate of increase in RPI – past service 3.60 3.15 2.65 n/a n/a n/a n/a n/a n/a Rate of increase in RPI – future service 3.33 3.00 2.45 n/a n/a n/a n/a n/a n/a Salary increases 3.47 3.40 2.90 4.60 4.30 3.50 4.60 4.30 3.50 Initial healthcare cost trend rate n/a n/a n/a n/a n/a n/a 6.80 7.10 7.00 Ultimate healthcare cost trend rate n/a n/a n/a n/a n/a n/a 4.50 4.50 4.50 The table below sets out the projected life expectancies adopted for the UK and US pension arrangements: UK pensions US pensions 2022 2021 2020 2022 2021 2020 years years years years years years Assumed life expectations for a retiree age 65 Males 22.0 21.8 22.1 21.4 21.6 20.9 Females 23.8 23.7 23.8 23.6 24.0 23.4 In 20 years: Males 23.2 23.1 23.3 23.1 23.2 22.5 Females 25.2 25.2 25.3 25.3 25.5 25.1 UK pensions US pensions US other 2022 2021 2022 2021 2022 2021 % % % % % % Active members 16 8 36 35 34 34 Deferred members 10 14 9 9 — — Pensioner members 74 78 55 56 66 66
Amounts recognised in the statement of financial position	Amounts recognised in the consolidated statement of financial position 2022 2021 £m £m Present value of funded obligations (23,541) (23,283) Fair value of plan assets 27,013 24,388 3,472 1,105 Present value of unfunded obligations (326) (324) Other post-employment liabilities (71) (66) Net defined benefit asset/(liability) 3,075 715 Represented by: Liabilities (810) (1,032) Assets 3,885 1,747 3,075 715 The geographical split of pensions and other post-retirement benefits is as shown below: UK pensions US pensions US other Total 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Present value of funded obligations (14,197) (13,571) (6,531) (6,681) (2,813) (3,031) (23,541) (23,283) Fair value of plan assets 16,865 14,680 7,263 6,909 2,885 2,799 27,013 24,388 2,668 1,109 732 228 72 (232) 3,472 1,105 Present value of unfunded obligations (78) (74) (248) (250) — — (326) (324) Other post-employment liabilities — — — — (71) (66) (71) (66) Net defined benefit asset/(liability) 2,590 1,035 484 (22) 1 (298) 3,075 715 Represented by: Liabilities (78) (74) (248) (393) (484) (565) (810) (1,032) Assets 2,668 1,109 732 371 485 267 3,885 1,747 2,590 1,035 484 (22) 1 (298) 3,075 715
Amounts recognised in the income statement and statement of other comprehensive income	Amounts recognised in the income statement and statement of other comprehensive income The expense or income arising from all Group retirement benefit arrangements recognised in the Group income statements is shown below: 2022 2021 2020 £m £m £m Included within operating costs Administration costs 20 18 16 Included within payroll costs Defined benefit plan costs: Current service cost 223 175 178 Past service cost – augmentations 1 — — Past service cost/(credit) – redundancies 1 (1) — Special termination benefit cost – redundancies 9 5 2 234 179 180 Included within finance income and costs Net interest (income)/cost (2) 38 23 Total included in income statement¹ 252 235 219 Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations 2 2,481 1,408 (724) Exchange adjustments 7 186 (97) Total included in the statement of other comprehensive income³ 2,488 1,594 (821) 1. Amounts shown in the table above include operating costs of £4 million (2021: £3 million; 2020: £4 million); payroll costs of £10 million (2021: £10 million; 2020: £10 million); and net interest income of £2 million (2021: £13 million; 2020: £11 million) presented within profit from discontinued operations. These amounts all relate to UK pensions. 2. For the year ended 31 March 2021, this included actuarial losses from the purchase of buy-in policies of £0.1 billion. 3. Amounts shown in the table above include remeasurements of pension assets and post-retirement benefit obligations resulting in a gain of £309 million (2021: £250 million loss; 2020: £58 million gain) presented within discontinued operations. These amounts all relate to UK pensions. The geographical split of pensions and other post-retirement benefits is shown below: UK pensions US pensions US other post-retirement benefits 2022 2021 2020 2022 2021 2020 2022 2021 2020 £m £m £m £m £m £m £m £m £m Included within operating costs Administration costs 11 9 9 7 7 6 2 2 1 Included within payroll costs Defined benefit plan costs: Current service cost 83 28 33 101 104 100 39 43 45 Past service cost – augmentations 1 — — — — — — — — Past service cost/(credit) – redundancies 1 (1) — — — — — — — Special termination benefit cost – redundancies 9 5 2 — — — — — — 94 32 35 101 104 100 39 43 45 Included within finance income and costs Net interest (income)/cost (7) (38) (31) — 35 21 5 41 33 Total included in income statement 98 3 13 108 146 127 46 86 79 Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations 1 1,577 (622) 143 532 1,017 (588) 372 1,013 (279) Exchange adjustments — — — 11 83 (42) (4) 103 (55) Total included in the statement of other comprehensive income 1,577 (622) 143 543 1,100 (630) 368 1,116 (334) 1. For the year ended 31 March 2021, UK pensions is stated after actuarial losses from the purchase of buy-in policies of £0.1 billion.
Reconciliation of the net defined benefit asset (liability)	Reconciliation of the net defined benefit asset/(liability) UK pensions US pensions US other Total 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Opening net defined benefit asset/(liability) 1,035 1,520 (22) (1,113) (298) (1,360) 715 (953) Cost recognised in the income statement (including discontinued operations) (98) (3) (108) (146) (46) (86) (252) (235) Remeasurement and foreign exchange effects recognised in the statement of other comprehensive income 1,577 (622) 543 1,100 368 1,116 2,488 1,594 Employer contributions 167 138 116 110 17 26 300 274 Other movements 7 2 — — (29) (16) (22) (14) Acquisition of WPD (note 37) 566 — — — — — 566 — Reclassification to held for sale (note 10) (664) — (45) 27 (11) 22 (720) 49 Closing net defined benefit asset/(liability) 2,590 1,035 484 (22) 1 (298) 3,075 715 Changes in the present value of defined benefit obligations (including unfunded obligations) The table below shows the movement in defined benefit obligations across our DB plans over the year. UK pensions US pensions US other Total 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Opening defined benefit obligations (13,645) (12,844) (6,931) (8,085) (3,031) (3,697) (23,607) (24,626) Current service cost (83) (28) (101) (104) (39) (43) (223) (175) Interest cost (88) (296) (240) (243) (100) (112) (428) (651) Actuarial (losses)/gains – experience (627) (21) (24) (72) 107 216 (544) 123 Actuarial gains/(losses) – demographic assumptions 133 (1) 100 — 71 — 304 (1) Actuarial gains/(losses) – financial assumptions 1,387 (1,181) 329 (62) 192 (25) 1,908 (1,268) Past service (cost)/credit – redundancies (1) 1 — — — — (1) 1 Special termination benefit cost – redundancies (9) (5) — — — — (9) (5) Past service cost – augmentations (1) — — — — — (1) — Medicare subsidy received — — — — (24) (25) (24) (25) Employee contributions (8) (1) — — — — (8) (1) Benefits paid 919 731 403 371 159 144 1,481 1,246 Exchange adjustments — — (327) 804 (140) 362 (467) 1,166 Acquisition of WPD (7,096) — — — — — (7,096) — Reclassification to held for sale 4,844 — 12 460 (8) 149 4,848 609 Closing defined benefit obligations (14,275) (13,645) (6,779) (6,931) (2,813) (3,031) (23,867) (23,607) 25. Pensions and other post-retirement benefits continued Changes in the value of plan assets The table below shows the movement in pension assets across our DB plans over the year. UK pensions US pensions US other Total 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m Opening fair value of plan assets 14,680 14,364 6,909 6,972 2,799 2,412 24,388 23,748 Interest income 95 334 240 208 95 71 430 613 Return on plan assets in excess of interest 1 684 581 127 1,151 2 822 813 2,554 Administration costs (11) (9) (7) (7) (2) (2) (20) (18) Employer contributions 167 138 116 110 17 26 300 274 Employee contributions 8 1 — — — — 8 1 Benefits paid (912) (729) (403) (371) (159) (144) (1,474) (1,244) Exchange adjustments — — 338 (721) 136 (259) 474 (980) Acquisition of WPD 7,662 — — — — — 7,662 — Reclassification to held for sale (5,508) — (57) (433) (3) (127) (5,568) (560) Closing fair value of plan assets 16,865 14,680 7,263 6,909 2,885 2,799 27,013 24,388 Actual return on plan assets 779 915 367 1,359 97 893 1,243 3,167 Expected contributions to plans 146 93 74 113 14 6 234 212 1. For the year ended 31 March 2021, this included actuarial losses from the purchase of buy-in policies of £0.1 billion.
Disclosure of asset allocations	The allocation of assets by asset class is set out below. Within these asset allocations there is significant diversification across regions, asset managers, currencies and bond categories. UK pensions 2022 2021 2020 Quoted Unquoted Total Quoted Unquoted Total Quoted Unquoted Total £m £m £m £m £m £m £m £m £m Equities 1,458 474 1,932 555 801 1,356 732 732 1,464 Corporate bonds 2,741 — 2,741 3,730 37 3,767 3,837 — 3,837 Government securities 786 — 786 1,836 — 1,836 2,051 — 2,051 Property 122 1,002 1,124 104 565 669 103 585 688 Diversified alternatives 1,334 432 1,766 — 712 712 — 893 893 Liability-matching assets 2,023 ¹ 6,090 ² 8,113 ³ 1,731 ¹ 4,133 ² 5,864 ³ 1,704 ¹ 3,278 ² 4,982 ³ Longevity swap — (80) (80) — (64) (64) — (51) (51) Cash and cash equivalents 477 — 477 34 250 284 29 222 251 Other (including net current assets and liabilities) 16 (10) 6 — 256 256 — 249 249 8,957 7,908 16,865 ⁴ 7,990 6,690 14,680 8,456 5,908 14,364 1. Consists of pooled funds which invest mainly in fixed interest securities. 2. Includes buy-in policies held by NGUKPS with a total value of £2.7 billion (2021: £4.1 billion; 2020: £3.3 billion). 3. Included within liability-matching assets above is £6.6 billion (2021: £2.5 billion; 2020: £2.8 billion) of repurchase agreements. These are used to increase the market exposure of the liability-matching portfolios. 4. The fair value of plan assets for NGUKPS Section A includes £32 million (2021: £nil; 2020: £nil) of direct holdings in WPD debt instruments. 25. Pensions and other post-retirement benefits continued US pensions 2022 2021 2020 Quoted Unquoted Total Quoted Unquoted Total Quoted Unquoted Total £m £m £m £m £m £m £m £m £m Equities 272 1,904 2,176 560 2,359 2,919 467 2,043 2,510 Corporate bonds 2,311 697 3,008 1,547 507 2,054 1,640 518 2,158 Government securities 335 715 1,050 354 527 881 535 732 1,267 Property — 295 295 — 264 264 — 307 307 Diversified alternatives 142 364 506 167 458 625 162 464 626 Infrastructure — 182 182 — 130 130 — 121 121 Cash and cash equivalents 31 — 31 24 — 24 24 — 24 Other (including net current assets and liabilities) 12 3 15 12 — 12 (44) 3 (41) 3,103 4,160 7,263 2,664 4,245 6,909 2,784 4,188 6,972 US other post-retirement benefits 2022 2021 2020 Quoted Unquoted Total Quoted Unquoted Total Quoted Unquoted Total £m £m £m £m £m £m £m £m £m Equities 185 1,013 1,198 419 1,303 1,722 353 1,037 1,390 Corporate bonds 723 2 725 13 — 13 15 — 15 Government securities 511 2 513 533 3 536 551 1 552 Diversified alternatives 144 120 264 185 172 357 162 161 323 Other¹ — 185 185 — 171 171 — 132 132 1,563 1,322 2,885 1,150 1,649 2,799 1,081 1,331 2,412 1. Other primarily comprises insurance contracts. The approximate investment allocations for our plans at 31 March 2022 are as follows: UK pensions US pensions US other post-retirement benefits % % % Return-seeking assets 28 41 51 Liability-matching assets 72 59 49
Disclosure of most significant risks associated with DB plans	The most significant risks associated with the DB plans are: Main risks Description and mitigation Investment risk The plans invest in a variety of asset classes, with actual returns likely to differ from the underlying discount rate adopted, impacting on the funding position of the plan through the net balance sheet asset or liability. Each plan seeks to balance the level of investment return required with the risk that it can afford to take, to design the most appropriate investment portfolio. Changes in bond yields Liabilities are calculated using discount rates set with reference to the yields in high-quality bonds prevailing in the UK and US debt markets and will fluctuate as yields change. Volatility of the net balance sheet asset or liability is controlled through liability-matching strategies. The investment strategies allow for the use of synthetic as well as physical assets to be used to hedge interest rate risk. Inflation risk Changes in inflation will affect the current and future pensions but are partially mitigated through investing in inflation-matching assets and hedging instruments as well as bulk annuity buy-in policies. The investment strategies allow for the use of synthetic as well as physical assets to be used to hedge inflation risk. Member longevity Longevity is a key driver of liabilities and changes in life expectancy have a direct impact on liabilities. Improvements in life expectancy will lead to pension payments being paid for longer than expected and benefits ultimately being more expensive. This risk has been partly mitigated by recent scheme investment transactions including a longevity insurance contract (longevity swap) for NGEG of ESPS and two buy-in policies for Section A of NGUKPS. Counterparty risk This is managed by having a diverse range of counterparties and through having a strong collateralisation process (including for the longevity swap held by NGEG of ESPS). Measurement and management of counterparty risk is delegated to the relevant investment managers. For our bulk annuity policies, various termination provisions were introduced in the contracts, managing our exposure to counterparty risk. The insurers’ operational performance and financial strength are monitored on a regular basis. Default risk Investments are predominantly made in regulated markets in assets considered to be of investment grade. Where investments are made either in non-investment grade assets or outside of regulated markets, investment levels are kept to prudent levels and subject to agreed control ranges, to control the risk. Liquidity risk The pension plans hold sufficient cash to meet benefit requirements, with other investments being held in liquid or realisable assets to meet unexpected cash flow requirements. The plans do not borrow money, or act as guarantor, to provide liquidity to other parties (unless it is temporary). Currency risk Fluctuations in the value of foreign denominated assets due to exposure to currency exchange rates is managed through a combination of segregated currency hedging overlay and currency hedging carried out by some of the investment managers.

Provisions (Tables)

Provisions (Tables)	12 Months Ended
	Mar. 31, 2022
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
Schedule of provisions	Environmental £m Decommissioning £m Restructuring £m Other £m Total provisions £m At 1 April 2020 2,071 254 35 294 2,654 Exchange adjustments (185) (9) (1) (21) (216) Additions 26 42 11 67 146 Unused amounts reversed (38) (27) — (16) (81) Unwinding of discount 66 7 — 5 78 Utilised (161) (16) (19) (62) (258) Reclassification to held for sale (note 10) (79) (7) — (10) (96) At 31 March 2021 1,700 244 26 257 2,227 Exchange adjustments 82 4 1 10 97 Additions 158 37 16 212 423 Acquisition of WPD (note 37) — 37 — 29 66 Unused amounts reversed (25) (4) (1) (31) (61) Unwinding of discount 64 6 — 3 73 Utilised (99) (26) (22) (47) (194) Reclassification to held for sale (note 10) (3) (40) (3) (46) (92) At 31 March 2022 1,877 258 17 387 2,539 2022 2021 £m £m Current 240 260 Non-current 2,299 1,967 2,539 2,227
Schedule of environmental provision	The environmental provision is as follows: 2022 2021 Discounted Real undiscounted Real Discounted Real undiscounted Real discount rate UK sites 152 160 0.5 % 167 171 0.5 % US sites 1,725 1,789 0.5 % 1,533 1,583 0.5 % 1,877 1,949 1,700 1,754

Share capital (Tables)

Share capital (Tables)	12 Months Ended
	Mar. 31, 2022
Share Capital, Reserves And Other Equity Interest [Abstract]
Schedule of share capital	Allotted, called-up and fully paid million £m At 1 April 2020 3,780 470 Issued during the year in lieu of dividends¹ 35 4 At 31 March 2021 3,815 474 Issued during the year in lieu of dividends¹ 89 11 At 31 March 2022 3,904 485 1. The issue of shares under the scrip dividend programme is considered to be a bonus issue under the terms of the Companies Act 2006, and the nominal value of the shares is charged to the share premium account.

Other equity reserves (Tables)

Other equity reserves (Tables)	12 Months Ended
	Mar. 31, 2022
Disclosure of reserves within equity [abstract]
Schedule of reserves within equity	Translation £m Cash flow hedge £m Cost of hedging £m FVOCI equity £m FVOCI Own Capital redemption £m Merger £m Total £m At 1 April 2019 750 61 17 34 48 13 19 (5,165) (4,223) Exchange adjustments¹ 560 — — — — — — — 560 Net losses taken to equity — (142) (33) (13) (15) (3) — — (206) Share of net losses of associates taken to equity — (5) — — — — — — (5) Transferred to profit or loss — 14 (45) — — — — — (31) Net losses in respect of cash flow hedging of capital expenditure — (17) — — — — — — (17) Tax — 29 11 4 (2) — — — 42 Cash flow hedges transferred to the statement of financial position, net of tax — (15) — — — — — — (15) At 1 April 2020 1,310 (75) (50) 25 31 10 19 (5,165) (3,895) Exchange adjustments¹ (1,345) — — — — — — — (1,345) Net gains/(losses) taken to equity — 14 11 36 80 (11) — — 130 Share of net gains of associates taken to equity — 1 — — — — — — 1 Transferred to profit or loss — 56 3 — — — — — 59 Net losses in respect of cash flow hedging of capital expenditure — (14) — — — — — — (14) Tax — (13) 8 (10) — 2 — — (13) Cash flow hedges transferred to the statement of financial position, net of tax — (17) — — — — — — (17) At 1 April 2021 (35) (48) (28) 51 111 1 19 (5,165) (5,094) Exchange adjustments¹ 629 — — — — — — — 629 Net losses taken to equity² — (96) (2) (70) (11) (1) — — (180) Share of net gains of associates taken to equity — 1 — — — — — — 1 Transferred to profit or loss — 40 (1) — — — — — 39 Net losses in respect of cash flow hedging of capital expenditure — (1) — — — — — — (1) Tax — 11 2 19 3 — — — 35 Cash flow hedges transferred to the statement of financial position, net of tax — 8 — — — — — — 8 At 31 March 2022 594 (85) (29) — 103 — 19 (5,165) (4,563) 1. The exchange adjustments recorded in the translation reserve comprise a gain of £754 million (2021: loss of £1,507 million; 2020: gain of £545 million) relating to the translation of foreign operations offset by a loss of £125 million (2021: gain of £183 million; 2020: gain of £5 million) relating to borrowings, cross-currency swaps and foreign exchange forward contracts used to hedge the net investment in non-sterling denominated subsidiaries.

Net debt (Tables)

Net debt (Tables)	12 Months Ended
	Mar. 31, 2022
Subclassifications of assets, liabilities and equities [abstract]
Schedule of components of net debt	Net debt is comprised as follows: 2022 2021 2020 £m £m £m Cash and cash equivalents (see note 20) 204 157 73 Current financial investments (see note 15) 3,145 2,342 1,998 Borrowings (see note 21) (45,465) (31,220) (30,794) Financing derivatives¹ (see note 17) (693) 175 133 (42,809) (28,546) (28,590) 1. The financing derivatives balance included in net debt excludes the commodity derivatives (see note 17).
Schedule of changes in net debt	Analysis of changes in net debt Notes Cash and cash equivalents £m Financial investments 1 £m Borrowings £m Financing derivatives £m Total 2 £m At 1 April 2019 252 1,981 (28,730) (32) (26,529) Impact of transition to IFRS 16 — — (474) — (474) Cash flow (183) (42) 450 450 675 Fair value gains and losses — 1 (57) (246) (302) Foreign exchange movements 4 24 (807) — (779) Interest income/(charges) 6 — 34 (1,092) (39) (1,097) Other non-cash movements — — (84) — (84) At 1 April 2020 73 1,998 (30,794) 133 (28,590) Cash flow 95 429 (2,336) 4 (1,808) Fair value gains and losses — 14 159 31 204 Foreign exchange movements (7) (106) 1,710 — 1,597 Interest income/(charges) 6 — 7 (946) 7 (932) Other non-cash movements — — (136) — (136) Reclassification to held for sale 10 (4) — 1,123 — 1,119 At 1 April 2021 157 2,342 (31,220) 175 (28,546) Cash flow 29(c) 9 752 (9,993) 262 (8,970) Fair value gains and losses — (12) 286 (604) (330) Foreign exchange movements 5 53 (652) — (594) Interest income/(charges) 6 — 43 (1,177) (59) (1,193) Other non-cash movements — (15) 34 — 19 Acquisition of WPD 37 44 69 (8,286) 26 (8,147) Reclassification to held for sale³ 10 (11) (87) 5,543 (493) 4,952 At 31 March 2022 204 3,145 (45,465) (693) (42,809) Balances at 31 March 2022 comprise: Non-current assets — — — 264 264 Current assets 204 3,145 — 34 3,383 Current liabilities — — (12,121) (136) (12,257) Non-current liabilities — — (33,344) (855) (34,199) 204 3,145 (45,465) (693) (42,809) 1. Cash flows on current financial investments comprise £29 million (2021: £7 million; 2020: £35 million) of interest received and £781 million of cash outflows (2021: £436 million outflows; 2020: £7 million outflows) of net cash flow movements in short-term financial investments, as presented in the consolidated cash flow statement. 2. Includes accrued interest at 31 March 2022 of £351 million (2021: £263 million; 2020: £246 million). 3. Reclassification to held for sale represents the opening net debt position of the UK Gas Transmission business. The closing net debt position of the UK Gas Transmission business is disclosed in note 10.
Reconciliation of cash flow from financing liabilities to cash flow statement	Reconciliation of cash flow from liabilities within net debt to cash flow statement 2022 2021 1 2020 1 Borrowings and other Financing derivatives Borrowings and other Financing derivatives Borrowings and other Financing derivatives Cash flows per financing activities section of cash flow statement: Proceeds received from loans 12,347 — 5,150 — 3,921 — Repayment of loans (1,261) — (1,654) — (3,037) — Payments of lease liabilities (117) — (107) — (115) — Net movements in short-term borrowings (11) — (619) — (562) — Cash inflows on derivatives — 20 — 17 — 46 Cash outflows on derivatives — (114) — (183) — (245) Interest paid (998) (55) (711) (42) (802) (65) Cash flows per financing activities section of cash flow statement 9,960 (149) 2,059 (208) (595) (264) Adjustments: Non-net debt-related items 33 — 29 — 34 — Derivative cash (outflow)/inflow in relation to capital expenditure — (8) — 10 — 13 Derivative cash inflows per investing section of cash flow statement — 17 — 225 — 58 Derivative cash outflows per investing section of cash flow statement — (122) — (81) — (281) Cash flows relating to financing liabilities within net debt 9,993 (262) 2,088 (54) (561) (474) Analysis of changes in net debt: Borrowings 9,993 — 2,088 — (561) — Financing derivatives — (262) — (54) — (474) Cash flow movements relating to financing liabilities within net debt 9,993 (262) 2,088 (54) (561) (474)
Reconciliation of changes in liabilities arising from financing activities	The table below reconciles changes in liabilities arising from financing activities, including both changes arising from cash flows and non-cash changes. For the purposes of this table, the liabilities arising from financing activities are those for which cash flows were, or future cash flows will be, classified in the consolidated cash flow statement within financing activities. As a result we have separately disclosed the reconciliation below, excluding derivatives associated with our net investment hedges and derivatives associated with the hedging of capital expenditure, given that they are both classified in the consolidated cash flow statement within investing activities. Notes Borrowings £m Financing derivatives £m Total £m At 1 April 2019 (28,730) 228 (28,502) Impact of transition to IFRS 16 (474) — (474) Cash flow¹ 450 240 690 Fair value gains and losses (57) (231) (288) Foreign exchange movements (807) — (807) Interest charges 6 (1,092) (9) (1,101) Other non-cash movements (84) — (84) At 1 April 2020 (30,794) 228 (30,566) Cash flow¹ (2,336) 158 (2,178) Fair value gains and losses 159 (301) (142) Foreign exchange movements 1,710 — 1,710 Interest charges 6 (946) 11 (935) Other non-cash movements (136) — (136) Reclassification to held for sale 10 1,123 — 1,123 At 1 April 2021 (31,220) 96 (31,124) Cash flow (9,993) 149 (9,844) Fair value gains and losses 286 (472) (186) Foreign exchange movements (652) — (652) Interest charges 6 (1,177) (54) (1,231) Other non-cash movements 34 — 34 Acquisition of WPD 37 (8,286) 26 (8,260) Reclassification to held for sale² 10 5,543 (495) 5,048 At 31 March 2022 (45,465) (750) (46,215) 1. Comparative amounts include financing cash flows attributable to the UK Gas Transmission business which was classified as a discontinued operation in the year (see notes 1 and 10). In order to reconcile financing cash flows to the consolidated cash flow statement for the years ended 31 March 2021 and 2020, cash flows from financing activities for both continuing operations and discontinued operations should be included, along with non-debt related items in note 29(c).

Commitments and contingencies (

Commitments and contingencies (Tables)	12 Months Ended
	Mar. 31, 2022
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
Schedule of capital commitments and contingent liabilities	2022 2021 £m £m Future capital expenditure Contracted for but not provided 1 2,881 2,716 Energy purchase commitments 2 Less than 1 year 1,386 1,255 In 1 to 2 years 1,366 894 In 2 to 3 years 1,219 975 In 3 to 4 years 1,189 959 In 4 to 5 years 1,088 896 More than 5 years 12,266 10,805 18,514 15,784 Guarantees Guarantee of sublease for US property (expires 2040) 149 149 Guarantees of certain obligations of Grain LNG (expire up to 2025) 31 33 Guarantees of certain obligations for construction of HVDC West Coast Link (expected expiry 2059) 84 85 Guarantees of certain obligations of National Grid North Sea Link Limited (various expiry dates) 569 584 Guarantees of certain obligations of St William Homes LLP (various expiry dates) 44 53 Guarantees of certain obligations of National Grid IFA 2 Limited (expected expiry 2022) 130 170 Guarantees of certain obligations of National Grid Viking Link Limited (expected expiry 2024) 1,177 1,276 Other guarantees and letters of credit (various expiry dates) 380 486 2,564 2,836 1. Included within future capital expenditure is £205 million (2021: £186 million) pertaining to the UK Gas Transmission business. 2. Energy purchase commitments relate to contractual commitments to purchase electricity or gas that are used to satisfy physical delivery requirements to our customers or for energy that we use ourselves (i.e. normal purchase, sale or usage) and hence are accounted for as ordinary purchase contracts (see note 32(f)). Details of commodity contract derivatives that do not meet the normal purchase, sale or usage criteria, and hence are accounted for as derivative contracts, are shown in note 17(b).

Related party transactions (Tab

Related party transactions (Tables)	12 Months Ended
	Mar. 31, 2022
Related party transactions [abstract]
Schedule of transactions between related parties	The following significant transactions with related parties were in the normal course of business. Amounts receivable from and payable to related parties are due on normal commercial terms: 2022 2021 2020 £m £m £m Sales: Goods and services supplied to a pension plan 3 3 5 Sales: Goods and services supplied to joint ventures¹ 284 79 101 Sales: Goods and services supplied to associates² — 1 33 Purchases: Goods and services received from joint ventures³ 19 35 61 Purchases: Goods and services received from associates³ 41 43 56 Receivable from joint ventures⁴ 43 263 255 Receivable from associates 1 — 1 Payable to joint ventures 5 247 17 — Payable to associates 4 3 4 Interest income from joint ventures — — 2 Interest income from associates — — 8 Dividends received from joint ventures 6 123 49 34 Dividends received from associates 7 35 32 41 1. During the year, £74 million of sales were made to Emerald Energy Venture LLC (2021: £50 million; 2020: £21 million) and a further £7 million (2021: £6 million; 2020; £32 million) of sales were made to NGET/SPT Upgrades Limited. Prior to the Group’s disposal of its equity interest in St William Homes LLP on 15 March 2022, a further £202 million (2021: £14 million; 2020: £38 million) of property sites were sold to St William Homes LLP. 2. In previous years, sales related to transactions with Quadgas, until the date it ceased to be a related party following the disposal of our 39% stake in June 2019 (see note 10) and included income of £31 million in 2020 relating to a Transitional Service Agreement following the sale of the UK Gas Distribution business to Quadgas. 3. During the year, the Group received goods and services from a number of US associates, both for the transportation of gas and for pipeline services in the US, most notably, £38 million (2021: £41 million; 2020: £31 million) of purchases from Millennium Pipeline Company LLC. The Group purchased assets of £18 million (2021: £17 million; 2020: £nil) from BritNed Development Limited. The Group also purchased assets of £0.3 million (2021: £5 million; 2020: £58 million) from NGET/SPT Upgrades Limited (a joint venture). 4. Amounts receivable from joint ventures include £33 million (2021: £19 million; 2020: £nil) from Emerald Energy Venture LLC. Amounts receivable in comparative periods include amounts due from St William Homes LLP, which is no longer a related party of the Group (2021: £241 million; 2020: £242 million). 5. Amounts payable to joint ventures include £223 million due to Bight Wind Holdings LLC, NGV’s joint venture with RWE Renewables, in respect of a capital call to NGV following the successful auction of six seabed leases in New York. 6. Includes dividends of £39 million (2021: £18 million; 2020: £25 million) received from BritNed Development Limited and £77 million (2021: £25 million; 2020: £8 million) from Nemo Link Limited. 7. Includes dividends of £34 million (2021: £31 million; 2020: £32 million) received from Millennium Pipeline Company LLC.

Financial risk management (Tabl

Financial risk management (Tables)	12 Months Ended
	Mar. 31, 2022
Financial Instruments [Abstract]
Disclosure of treasury credit risk	As at 31 March 2022, the following limits were in place for investments and derivative financial instruments held with banks and financial institutions: Maximum limit Long-term limit Triple ‘A’ G7 sovereign entities (AAA) 2,708 2,031 Triple ‘A’ vehicles (AAA) 500 — Triple ‘A’ range institutions and non-G7 sovereign entities (AAA) 2,462 1,847 Double ‘A+’ G7 sovereign entities (AA+) 2,462 1,847 Double ‘A’ range institutions (AA) 1,477 to 1,970 1,108 to 1,477 Single ‘A’ range institutions (A) 492 to 985 369 to 739
Disclosure of offsetting of financial assets and financial liabilities	Related amounts At 31 March 2022 Gross Gross Net amount Financial instruments Cash Net amount Assets Financing derivatives 298 — 298 (136) (55) 107 Commodity contract derivatives 289 — 289 (8) (50) 231 587 — 587 (144) (105) 338 Liabilities Financing derivatives (991) — (991) 136 771 (84) Commodity contract derivatives (22) — (22) 8 3 (11) (1,013) — (1,013) 144 774 (95) (426) — (426) — 669 243 Related amounts At 31 March 2021 Gross carrying amounts £m Gross Net amount presented in statement of financial position £m Financial instruments £m Cash collateral received/ pledged £m Net amount £m Assets Financing derivatives 942 — 942 (234) (561) 147 Commodity contract derivatives 57 — 57 (8) — 49 999 — 999 (242) (561) 196 Liabilities Financing derivatives (767) — (767) 234 467 (66) Commodity contract derivatives (132) — (132) 8 4 (120) (899) — (899) 242 471 (186) 100 — 100 — (90) 10
Disclosure of maturity analysis for financial liabilities and derivatives	The following is a payment profile of our financial liabilities and derivatives: At 31 March 2022 Less than £m 1 to 2 2 to 3 More than Total Non-derivative financial liabilities Borrowings, excluding lease liabilities (11,589) (1,322) (2,468) (28,119) (43,498) Interest payments on borrowings¹ (970) (928) (883) (12,525) (15,306) Lease liabilities (132) (96) (79) (366) (673) Other non-interest-bearing liabilities (3,979) (336) — — (4,315) Contingent consideration (37) (8) — — (45) Derivative financial liabilities Financing derivatives – receipts² 3,149 1,008 2,075 4,726 10,958 Financing derivatives – payments² (3,401) (1,189) (2,336) (5,468) (12,394) Commodity contract derivatives – receipts² 1 1 — — 2 Commodity contract derivatives – payments² (29) 2 (1) — (28) Derivative financial assets Financing derivatives – receipts² 4,512 316 1,427 464 6,719 Financing derivatives – payments² (4,405) (282) (1,313) (405) (6,405) Commodity contract derivatives – receipts² 234 37 3 — 274 Commodity contract derivatives – payments² (52) (8) (3) — (63) (16,698) (2,805) (3,578) (41,693) (64,774) At 31 March 2021 Less than 1 year £m 1 to 2 2 to 3 years £m More than 3 years £m Total £m Non-derivative financial liabilities Borrowings, excluding lease liabilities (3,350) (1,690) (806) (25,562) (31,408) Interest payments on borrowings¹ (810) (755) (731) (12,018) (14,314) Lease liabilities (118) (108) (90) (599) (915) Other non-interest-bearing liabilities (3,207) (350) — — (3,557) Contingent consideration (40) (24) — — (64) Derivative financial liabilities Financing derivatives – receipts² 3,773 749 451 4,326 9,299 Financing derivatives – payments² (3,899) (877) (533) (5,153) (10,462) Commodity contract derivatives – receipts² 12 — — — 12 Commodity contract derivatives – payments² (83) (23) (14) (12) (132) Derivative financial assets Financing derivatives – receipts² 2,162 926 833 1,789 5,710 Financing derivatives – payments² (1,700) (834) (780) (1,536) (4,850) Commodity contract derivatives – receipts² 21 4 1 1 27 Commodity contract derivatives – payments² (21) (4) (2) — (27) (7,260) (2,986) (1,671) (38,764) (50,681) 1. The interest on borrowings is calculated based on borrowings held at 31 March without taking account of future issues. Floating rate interest is estimated using a forward interest rate curve as at 31 March. Payments are included on the basis of the earliest date on which the Company can be required to settle. 2. The receipts and payments line items for derivatives comprise gross undiscounted future cash flows, after considering any contractual netting that applies within individual contracts. Where cash receipts and payments within a derivative contract are settled net, and the amount to be received/(paid) exceeds the amount to be paid/(received), the net amount is presented within derivative receipts/(payments).
Disclosure of nature and extent of risks arising from financial instruments	Derivative financial instruments were used to manage foreign currency risk as follows: 2022 2021 Sterling Euro Dollar Other Total Sterling £m Euro £m Dollar £m Other £m Total £m Cash and cash equivalents 111 — 93 — 204 63 — 94 — 157 Financial investments 1,725 — 1,420 — 3,145 1,215 — 1,127 — 2,342 Borrowings (22,910) (7,052) (14,118) (1,385) (45,465) (12,210) (5,351) (12,660) (999) (31,220) Pre-derivative position (21,074) (7,052) (12,605) (1,385) (42,116) (10,932) (5,351) (11,439) (999) (28,721) Derivative effect (1,378) 6,849 (7,570) 1,406 (693) (826) 5,459 (5,494) 1,036 175 Net debt position (22,452) (203) (20,175) 21 (42,809) (11,758) 108 (16,933) 37 (28,546) The currency exposure on other financial instruments is as follows: 2022 2021 Sterling Euro Dollar Other Total Sterling £m Euro £m Dollar £m Other £m Total £m Trade and other receivables 407 — 1,788 — 2,195 282 — 1,387 — 1,669 Trade and other payables (1,459) — (2,554) — (4,013) (1,207) — (1,878) — (3,085) Other non-current liabilities (90) — (253) — (343) (77) — (288) — (365) The table below sets out the sensitivity analysis for certain areas of estimation uncertainty set out in note 1F. These estimates are those that have a significant risk of resulting in a material adjustment to the carrying values of assets and liabilities in the next year. Note that the sensitivity analysis for the useful economic lives of our gas network assets is included in note 13. 2022 2021 Income Net Income statement £m Net assets £m Pensions and other post-retirement benefit liabilities (pre-tax)¹: UK discount rate change of 0.5%² 12 1,002 4 952 US discount rate change of 0.5%² 16 650 17 730 UK RPI rate change of 0.5%³ 11 733 3 723 UK long-term rate of increase in salaries change of 0.5% 4 88 1 42 US long-term rate of increase in salaries change of 0.5% 3 41 3 42 UK change of one year to life expectancy at age 65 4 4 635 1 612 US change of one year to life expectancy at age 65 3 444 4 429 Assumed US healthcare cost trend rates change of 1% 24 414 26 437 Environmental provision: 10% change in estimated future cash flows 188 188 170 170 1. The changes shown are a change in the annual pension and other post-retirement benefit service charge and change in the defined benefit obligations. 2. A change in the discount rate is likely to occur as a result of changes in bond yields and as such would be expected to be offset to a significant degree by a change in the value of the bond assets held by the plans. In the UK, there would also be a £164 million (2021: £257 million) net assets offset from the buy-in policies, where the accounting value of the buy-in asset is set equal to the associated liabilities. 3. The projected impact resulting from a change in RPI reflects the underlying effect on pensions in payment, pensions in deferment and resultant increases in salary assumptions. The buy-in policies would have a £119 million (2021: £190 million) net assets offset to the above. 4. In the UK, the buy-in policies and the longevity swap entered into would have a £111 million (2021: £183 million) net assets offset to the above. 2022 2021 Income Other equity Income statement £m Other equity reserves £m Financial risk (post-tax): UK RPI change of 0.5%¹ 18 — 25 — UK interest rates change of 0.5% 41 134 12 98 US interest rates change of 0.5% 4 8 6 22 US dollar exchange rate change of 10%² 43 397 44 285 1. Excludes sensitivities to LPI curve. Further details on sensitivities are provided in note 32(g). 2. The other equity reserves impact does not reflect the exchange translation in our US subsidiaries’ net assets. It is estimated this would change by £1,670 million (2021: £1,425 million) in the opposite direction if the dollar exchange rate changed by 10%. Our commodity contract derivatives are sensitive to price risk. Additional sensitivities in respect to commodity price risk and to our derivative fair values are as follows: 2022 2021 Income Net Income statement £m Net assets £m Commodity price risk (post-tax): 10% increase in commodity prices 53 53 20 20 10% decrease in commodity prices (54) (54) (21) (21) Assets and liabilities carried at fair value (post-tax): 10% fair value change in derivative financial instruments¹ (55) (55) 14 14 10% fair value change in commodity contract derivative liabilities 20 20 6 6
Disclosure of financial instruments by type of interest rate	Net debt was managed using derivative financial instruments to hedge interest rate risk as follows: 2022 2021 Fixed rate £m Floating rate £m Inflation linked £m Other 1 £m Total £m Fixed rate £m Floating rate £m Inflation linked £m Other 1 £m Total £m Cash and cash equivalents 82 118 — 4 204 64 67 — 26 157 Financial investments — 3,107 — 38 3,145 — 2,309 — 33 2,342 Borrowings (30,616) (10,484) (4,365) — (45,465) (23,163) (1,762) (6,295) — (31,220) Pre-derivative position (30,534) (7,259) (4,365) 42 (42,116) (23,099) 614 (6,295) 59 (28,721) Derivative effect 2,860 (3,366) (187) — (693) 2,869 (2,511) (183) — 175 Net debt position (27,674) (10,625) (4,552) 42 (42,809) (20,230) (1,897) (6,478) 59 (28,546) 1. Represents financial instruments which are not directly affected by interest rate risk, such as investments in equity or other similar financial instruments.
Disclosure of detailed information about hedging instruments	In accordance with the requirements of IFRS 7, certain additional information about hedge accounting is disaggregated by risk type and hedge designation type in the tables below: Year ended 31 March 2022 Fair value hedges of foreign currency and interest rate risk Cash flow hedges of foreign currency and interest rate risk Cash flow hedges of foreign currency risk Net investment hedges Consolidated statement of comprehensive income Net gains/(losses) in respect of: Cash flow hedges — (103) (1) — Cost of hedging (7) 16 — (7) Transferred to profit or loss in respect of: Cash flow hedges — 43 — — Cost of hedging 1 — — (2) Consolidated statement of changes in equity Other equity reserves – cost of hedging balances (15) (16) — (3) Consolidated statement of financial position Derivatives – carrying value of hedging instruments ¹ Assets – current — — 1 10 Assets – non-current 49 67 1 82 Liabilities – current (21) (22) (37) (16) Liabilities – non-current (310) (303) (8) — Profiles of the significant timing, price and rate information of hedging instruments Maturity range Jul 2022 – Sep 2044 Jun 2022 – Nov 2040 Apr 2022 – Feb 2027 Sep 2022 – Sep 2027 Spot foreign exchange range: GBP:USD n/a 1.30 – 1.66 1.34 – 1.41 1.22 – 1.34 GBP:EUR 1.11 – 1.24 1.08 – 1.24 1.04 – 1.19 1.18 EUR:USD 1.13 – 1.17 1.13 – 1.15 n/a n/a Interest rate range: GBP SONIA +84bps/+374bps 0.976% – 7.410% n/a n/a USD LIBOR +68bps/+115bps 2.095% – 3.864% n/a n/a 1. The use of derivatives may entail a derivative transaction qualifying for more than one hedge type designation under IFRS 9. Therefore, the derivative amounts in the table above are grossed up by hedge type, whereas they are presented net at an instrument level in the statement of financial position. Year ended 31 March 2021 Fair value hedges of foreign currency and interest rate risk Cash flow hedges of Cash flow hedges of Net investment hedges Consolidated statement of comprehensive income Net losses in respect of: Cash flow hedges — 14 (14) — Cost of hedging (15) (24) — 50 Transferred to profit or loss in respect of: Cash flow hedges — 56 — — Cost of hedging 1 2 — — Consolidated statement of changes in equity Other equity reserves – cost of hedging balances (11) (30) — 6 Consolidated statement of financial position Derivatives – carrying value of hedging instruments¹ Assets – current — 10 2 5 Assets – non-current 187 59 1 140 Liabilities – current — (12) (24) (17) Liabilities – non-current (113) (255) (22) — Profiles of the significant timing, price and rate information of hedging instruments Maturity range Jan 2023 – Jan 2043 Sep 2021 – Nov 2040 Apr 2021 – Feb 2027 Mar 2022 – Sep 2027 Spot foreign exchange range: GBP:USD 1.64 1.30 – 1.66 1.31 – 1.41 1.22 – 1.40 GBP:EUR 1.11 – 1.24 1.08 – 1.24 1.04 – 1.29 1.15 – 1.16 EUR:USD 1.13 – 1.17 1.13 – 1.14 n/a n/a Interest rate range: GBP LIBOR +30bps/+408bps 0.976% – 5.845% n/a n/a USD LIBOR –68bps/+115bps 2.513% – 3.864% n/a n/a 1. The use of derivatives may entail a derivative transaction qualifying for more than one hedge type designation under IFRS 9. Therefore, the derivative amounts in the table above are grossed up by hedge type, whereas they are presented net at an instrument level in the statement of financial position. The following tables show the effects of hedge accounting on financial position and year-to-date performance for each type of hedge. These tables also present notional values of hedging instruments (and equal hedged exposures) impacted by IFRS 9 Interest Rate Benchmark Reform amendments. (i) Fair value hedges of foreign currency and interest rate risk on recognised borrowings: As at 31 March 2022 Balance of fair value hedge adjustments in borrowings Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings 1,2 (3,362) 437 (55) 340 (301) 39 1. The carrying value of the hedged borrowings is £2,966 million, of which £nil is current and £2,966 million is non-current. 2. Included within the hedging instrument notional balance is £2,556 million impacted by Interest Rate Benchmark Reform amendments with £806 million still to be transitioned. As at 31 March 2021 Balance of fair value hedge adjustments in borrowings Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings 1,2 (2,755) 121 (85) 153 (127) 26 1. The carrying value of the hedged borrowings was £2,714 million, of which £nil was current and £2,714 million was non-current. 2. Included within the hedging instrument notional balance was £2,679 million impacted by Interest Rate Benchmark Reform amendments. (ii) Cash flow hedges of foreign currency and interest rate risk: As at 31 March 2022 Balance in cash flow hedge reserve Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings ¹ (6,287) (48) — 74 (74) — Foreign currency risk on forecasted cash flows (835) (40) 1 18 (18) — 1. Included within the hedging instrument notional balance is £100 million impacted by Interest Rate Benchmark Reform amendments. As at 31 March 2021 Balance in cash flow hedge reserve Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings ¹ (4,884) (11) (6) (16) 16 — Foreign currency risk on forecasted cash flows (988) (31) 3 17 (17) — 1. Included within the hedging instrument notional balance was £176 million impacted by Interest Rate Benchmark Reform amendments. (iii) Net investment hedges of foreign currency risk: As at 31 March 2022 Balance in translation reserve Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Currency risk on foreign operations ¹ (3,489) (125) (2,643) 125 (125) — 1. Included within the hedging instrument notional balance is £nil impacted by Interest Rate Benchmark Reform amendments. As at 31 March 2021 Balance in translation reserve Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Currency risk on foreign operations¹ (2,786) 183 (2,826) (183) 183 — 1. Included within the hedging instrument notional balance was £nil impacted by Interest Rate Benchmark Reform amendments.
Disclosure of detailed information about hedged items	The following tables show the effects of hedge accounting on financial position and year-to-date performance for each type of hedge. These tables also present notional values of hedging instruments (and equal hedged exposures) impacted by IFRS 9 Interest Rate Benchmark Reform amendments. (i) Fair value hedges of foreign currency and interest rate risk on recognised borrowings: As at 31 March 2022 Balance of fair value hedge adjustments in borrowings Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings 1,2 (3,362) 437 (55) 340 (301) 39 1. The carrying value of the hedged borrowings is £2,966 million, of which £nil is current and £2,966 million is non-current. 2. Included within the hedging instrument notional balance is £2,556 million impacted by Interest Rate Benchmark Reform amendments with £806 million still to be transitioned. As at 31 March 2021 Balance of fair value hedge adjustments in borrowings Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings 1,2 (2,755) 121 (85) 153 (127) 26 1. The carrying value of the hedged borrowings was £2,714 million, of which £nil was current and £2,714 million was non-current. 2. Included within the hedging instrument notional balance was £2,679 million impacted by Interest Rate Benchmark Reform amendments. (ii) Cash flow hedges of foreign currency and interest rate risk: As at 31 March 2022 Balance in cash flow hedge reserve Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings ¹ (6,287) (48) — 74 (74) — Foreign currency risk on forecasted cash flows (835) (40) 1 18 (18) — 1. Included within the hedging instrument notional balance is £100 million impacted by Interest Rate Benchmark Reform amendments. As at 31 March 2021 Balance in cash flow hedge reserve Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Foreign currency and interest rate risk on borrowings ¹ (4,884) (11) (6) (16) 16 — Foreign currency risk on forecasted cash flows (988) (31) 3 17 (17) — 1. Included within the hedging instrument notional balance was £176 million impacted by Interest Rate Benchmark Reform amendments. (iii) Net investment hedges of foreign currency risk: As at 31 March 2022 Balance in translation reserve Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Currency risk on foreign operations ¹ (3,489) (125) (2,643) 125 (125) — 1. Included within the hedging instrument notional balance is £nil impacted by Interest Rate Benchmark Reform amendments. As at 31 March 2021 Balance in translation reserve Change in value used for calculating ineffectiveness Hedging instrument notional Continuing hedges Discontinued hedges Hedged item Hedging instrument Hedge ineffectiveness Hedge type £m £m £m £m £m £m Currency risk on foreign operations¹ (2,786) 183 (2,826) (183) 183 — 1. Included within the hedging instrument notional balance was £nil impacted by Interest Rate Benchmark Reform amendments.
Disclosure of fair value measurement of assets	2022 2021 Level 1 Level 2 Level 3 Total Level 1 £m Level 2 £m Level 3 £m Total £m Assets Investments held at FVTPL 2,292 — 417 2,709 1,768 — 240 2,008 Investments held at FVOCI¹ — 413 — 413 99 416 — 515 Financing derivatives — 298 — 298 — 942 — 942 Commodity contract derivatives — 238 51 289 — 12 45 57 2,292 949 468 3,709 1,867 1,370 285 3,522 Liabilities Financing derivatives — (804) (187) (991) — (584) (183) (767) Commodity contract derivatives — (15) (7) (22) — (75) (57) (132) Liabilities held at fair value — — — — (682) — — (682) Contingent consideration² — — (41) (41) — — (57) (57) — (819) (235) (1,054) (682) (659) (297) (1,638) 2,292 130 233 2,655 1,185 711 (12) 1,884 1. Investments held includes instruments which meet the criteria of IFRS 9 or IAS 19. 2. Contingent consideration relates to the acquisition of National Grid Renewables. The changes in value of our Level 3 financial instruments are as follows: Financing derivatives Commodity contract Other 3 Total 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m At 1 April (183) (235) (12) 2 183 137 (12) (96) Net gains/(losses) for the year 1,2 (4) 51 56 (16) 102 (2) 154 33 Purchases — — 17 (1) 93 32 110 31 Settlements — 1 (17) (1) (2) 16 (19) 16 Reclassification to held for sale (note 10) — — — 4 — — — 4 At 31 March (187) (183) 44 (12) 376 183 233 (12) 1. Loss of £4 million (2021: £51 million gain) is attributable to derivative financial instruments held at the end of the reporting period and has been recognised in finance costs in the income statement. 2. Gain of £27 million (2021: £46 million loss) is attributable to commodity contract derivative financial instruments held at the end of the reporting period. 3. Other comprises our investments in Sunrun Neptune 2016 LLC and the investments made by National Grid Partners, which are accounted for at fair value through profit and loss as well as the contingent consideration arising from the acquisition of National Grid Renewables.
Disclosure of fair value measurement of liabilities	2022 2021 Level 1 Level 2 Level 3 Total Level 1 £m Level 2 £m Level 3 £m Total £m Assets Investments held at FVTPL 2,292 — 417 2,709 1,768 — 240 2,008 Investments held at FVOCI¹ — 413 — 413 99 416 — 515 Financing derivatives — 298 — 298 — 942 — 942 Commodity contract derivatives — 238 51 289 — 12 45 57 2,292 949 468 3,709 1,867 1,370 285 3,522 Liabilities Financing derivatives — (804) (187) (991) — (584) (183) (767) Commodity contract derivatives — (15) (7) (22) — (75) (57) (132) Liabilities held at fair value — — — — (682) — — (682) Contingent consideration² — — (41) (41) — — (57) (57) — (819) (235) (1,054) (682) (659) (297) (1,638) 2,292 130 233 2,655 1,185 711 (12) 1,884 1. Investments held includes instruments which meet the criteria of IFRS 9 or IAS 19. 2. Contingent consideration relates to the acquisition of National Grid Renewables. The changes in value of our Level 3 financial instruments are as follows: Financing derivatives Commodity contract Other 3 Total 2022 2021 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m £m £m At 1 April (183) (235) (12) 2 183 137 (12) (96) Net gains/(losses) for the year 1,2 (4) 51 56 (16) 102 (2) 154 33 Purchases — — 17 (1) 93 32 110 31 Settlements — 1 (17) (1) (2) 16 (19) 16 Reclassification to held for sale (note 10) — — — 4 — — — 4 At 31 March (187) (183) 44 (12) 376 183 233 (12) 1. Loss of £4 million (2021: £51 million gain) is attributable to derivative financial instruments held at the end of the reporting period and has been recognised in finance costs in the income statement. 2. Gain of £27 million (2021: £46 million loss) is attributable to commodity contract derivative financial instruments held at the end of the reporting period. 3. Other comprises our investments in Sunrun Neptune 2016 LLC and the investments made by National Grid Partners, which are accounted for at fair value through profit and loss as well as the contingent consideration arising from the acquisition of National Grid Renewables.
Sensitivity analysis for types of market risk	The impacts on a post-tax basis of reasonably possible changes in significant Level 3 assumptions are as follows: Financing derivatives Commodity contract derivatives Other 3 2022 2021 2022 2021 2022 2021 £m £m £m £m £m £m 10% increase in commodity prices¹ — — 9 3 — — 10% decrease in commodity prices¹ — — (8) (1) — — +10% market area price change — — — (4) — — -10% market area price change — — — 7 — — +20 basis points change in Limited Price Inflation (LPI) market curve² (84) (83) — — — — -20 basis points change in LPI market curve² 82 83 — — — — +50 basis points change in discount rate — — — — (10) (5) -50 basis points change in discount rate — — — — 10 5 1. Level 3 commodity price sensitivity is included within the sensitivity analysis disclosed in note 35. 2. A reasonably possible change in assumption of other Level 3 derivative financial instruments is unlikely to result in a material change in fair values. 3. The investments acquired in the period were on market terms, and sensitivity is considered insignificant at 31 March 2022.

Borrowing facilities (Tables)

Borrowing facilities (Tables)	12 Months Ended
	Mar. 31, 2022
Disclosure of detailed information about borrowings [abstract]
Schedule of undrawn committed borrowing facilities	An analysis of the maturity of these undrawn committed facilities is shown below: 2022 2021 £m £m Undrawn committed borrowing facilities expiring: Less than 1 year — — In 1 to 2 years 936 1,668 In 2 to 3 years 4,373 534 In 3 to 4 years 1,605 1,718 In 4 to 5 years — 1,605 More than 5 years — — 6,914 5,525

Subsidiary undertakings, join_2

Subsidiary undertakings, joint ventures and associates (Tables)	12 Months Ended
	Mar. 31, 2022
Interests In Other Entities [Abstract]
Disclosure of interests in subsidiaries, associates and joint ventures	Birch Sites Limited Carbon Sentinel Limited Central Networks Trustees Limited 1 Droylsden Metering Services Limited Gridcom Limited Hyder Profit Sharing Trustees Limited 1 Icelink Interconnector Limited Kelston Properties 2 Limited 1 Lattice Group Employee Benefit Trust Limited Lattice Group Limited Lattice Group Trustees Limited Meter Operator Services Limited* 1 Meter Reading Services Limited* 1 Natgrid Limited NatGrid One Limited 2 NatgridTW1 Limited 2 National Grid (US) Holdings Limited 2 National Grid (US) Investments 2 Limited 2 National Grid (US) Investments 4 Limited 2 National Grid (US) Partner 1 Limited 2 National Grid Carbon Limited National Grid Commercial Holdings Limited National Grid Distributed Energy Limited National Grid Electricity Group Trustee Limited National Grid Electricity System Operator Limited National Grid Electricity Transmission plc National Grid Energy Metering Limited National Grid Gas Holdings Limited National Grid Gas plc National Grid Grain LNG Limited National Grid Holdings Limited 2 National Grid Holdings One plc National Grid Hydrogen Limited National Grid IFA 2 Limited National Grid Interconnector Holdings Limited National Grid Interconnectors Limited National Grid International Limited 2 National Grid Metering Limited National Grid North Sea Link Limited National Grid Offshore Limited National Grid Partners Limited National Grid Plus Limited National Grid Property Holdings Limited National Grid Smart Limited National Grid Ten National Grid Thirty Six Limited National Grid Twelve Limited 2 National Grid Twenty Eight Limited National Grid Twenty Seven Limited National Grid Twenty Three Limited 2 National Grid UK Limited National Grid UK Pension Services Limited National Grid Ventures Limited National Grid Viking Link Limited National Grid William Limited NG Nominees Limited NGC Employee Shares Trustee Limited NGG Finance plc Ngrid Intellectual Property Limited NGT Two Limited Port Greenwich Limited Sheet Road Management Company Limited (51%) 3 South Wales Electricity Share Scheme Trustees Limited 1 South Western Helicopters Limited 1 Supergrid Electricity Limited Supergrid Energy Transmission Limited Supergrid Limited Thamesport Interchange Limited The National Grid Group Quest Trustee Company Limited The National Grid YouPlan Trustee Limited Transco Limited Warwick Technology Park Management Company (No 2) Limited (60.56%) 4 Western Power Distribution (East Midlands) plc 1 Western Power Distribution (South Wales) plc 1 Western Power Distribution (South West) plc 1 Western Power Distribution (West Midlands) plc 1 Western Power Distribution Holding Company Limited 1 Western Power Distribution Investments Limited 1 Western Power Distribution plc 1 Western Power Generation Limited 1 Western Power Pension Trustee Limited 1 WPD Distribution Network Holdings Limited 1 WPD Investment Holdings limited 1 WPD Island Limited 1 WPD Limited 1 WPD Midlands Limited 1 WPD Midlands Networks Contracting Limited* 1 WPD Property Investments Limited 1 WPD Share Scheme Trustees Limited 1 WPD Smart Metering Limited 1 WPD Telecoms Limited 1 WPD WEM Holdings Limited 1 WPD WEM Limited 1 WW Share Scheme Trustees Limited 1 1. Registered office: Avonbank, Feeder Road, Bristol, Avon, BS2 0TB. 2. Companies where National Grid plc has issued guarantees over the liabilities of the companies as at 31 March 2022 and for which the companies are taking the exemption from the requirements of an audit for their individual financial statements as permitted by section 479A of the Companies Act. 3. Registered office: Netley Old Hall Farm, Dorrington, Shrewsbury, United Kingdom, SY5 7JY. 4. Registered office: Shire Hall, PO Box 9, Warwick CV34 4RL, UK. * In process of strike-off. Incorporated in the US Registered office: National Registered Agents, Inc., 1209 Orange Street, Wilmington, DE 19801, USA (unless stated otherwise in footnotes). Apple River Solar, LLC Armenia Solar, LLC Ashland Solar, LLC Athens Solar, LLC Autauga Solar, LLC Banner Solar, LLC Bazile Creek Wind Farm, LLC Bee Hollow Solar, LLC Bell Plaine Solar, LLC Benevolent Solar, LLC Blaze Solar, LLC 1 Blevins Solar, LLC Blue Ridge Wind, LLC Blue Spring Solar, LLC Blues Solar, LLC Bluewater Solar, LLC Boone Solar, LLC Boston Gas Company 2 Bridges Solar, LLC British Transco Capital, Inc. 3 British Transco Finance, Inc. 3 Brock Solar, LLC Broken Bridge Corp. 4 Brook Trout Solar, LLC Burley Solar, LLC Burlington Solar, LLC Burr Ridge Wind, LLC Cage Ranch Solar II, LLC Cage Ranch Solar III, LLC Cage Ranch Solar, LLC Caldwell Solar II, LLC Caldwell Solar, LLC Canby Solar, LLC Cass Wind Farm, LLC Cattle Ridge Wind Farm 2, LLC Cedar Grove Solar, LLC Centennial Solar, LLC Clay Boswell Solar, LLC Clear Creek Solar, LLC Clermont Solar, LLC Clinton County Solar, LLC Coles Solar, LLC Compass Prairie Wind, LLC Coneflower Solar, LLC 5 Conestoga Wind, LLC Copperhead Solar, LLC Creekview Solar, LLC Crocker Wind Farm 2, LLC Dahlia Solar, LLC 5 Dakota Hills Wind Farm, LLC Day Lily Solar, LLC 5 Deatsville Solar, LLC Deer Trail Solar, LLC Dodson Creek Solar, LLC 6 Donnellson Solar, LLC Elburn Solar, LLC Eldena Solar, LLC Elk Creek Solar 2, LLC Elk Creek Solar, LLC EUA Energy Investment Corporation 2 Exie Solar, LLC Falls City Solar, LLC Fayette Solar, LLC 7 Fillmore County Solar Project, LLC Firstview Wind Farm, LLC Fort Solar, LLC Front Range Wind Farm, LLC Gardenia Solar, LLC 5 Golden Solar, LLC Goldendale Solar, LLC Goldenrod Wind Farm, LLC Goldfinch Solar, LLC Grand Junction Solar, LLC Granite State Power Link LLC 3 Grant Solar 2, LLC Grant Solar, LLC Grayson Solar, LLC Greenbrier Creek Solar, LLC Greensky Solar, LLC Greenwood Solar, LLC Grid NY LLC 8 Grindstone Wind Farm, LLC 9 Hale County Solar, LLC Hansford Energy Storage, LLC Harmony Solar ND 2, LLC Harmony Solar ND, LLC Harrington Solar, LLC Hartley Solar, LLC Hearth Solar, LLC Hill River Solar, LLC Honeybee Solar, LLC Hoosier Solar, LLC Hoskins Solar, LLC Illumination Solar, LLC Innovation Solar, LLC Itasca Energy Development, LLC 5 Itasca Energy Services, LLC Jack Rabbit Wind, LLC Jackson County Solar, LLC Junction Solar, LLC KeySpan CI Midstream Limited 3 KeySpan Energy Corporation 8 KeySpan Energy Services Inc. 3 KeySpan Gas East Corporation 8 KeySpan International Corporation 3 KeySpan MHK, Inc. 3 KeySpan Midstream Inc. 3 KeySpan Plumbing Solutions, Inc. 8 Knox Solar, LLC KSI Contracting, LLC 3 KSI Electrical, LLC 3 KSI Mechanical, LLC 3 Lake Charlotte Solar, LLC Lake Iris Solar, LLC Lakeside Solar, LLC Land Management & Development, Inc. 8 Landwest, Inc. 8 Lansing Solar, LLC Leola Wind Farm, LLC Liberty Solar, LLC Lilac Solar, LLC 5 Livingston County Solar, LLC Long Mount Solar, LLC Lordsburg Solar, LLC Louisa Solar, LLC Lowlands Solar, LLC Lydia Solar, LLC Marion County Solar, LLC Massachusetts Electric Company 2 Maverick Wind Farm, LLC Meadowlands Solar, LLC Metrowest Realty LLC 3 Miller Creek Solar, LLC Millers Ferry Solar, LLC Morgan County Solar, LLC Morning Glory Solar, LLC 5 Muddy Creek Solar, LLC Mustang Ridge Wind Farm, LLC Mystic Steamship Corporation 6 Nantucket Electric Company 2 National Grid Development Holdings Corp. 3 National Grid Electric Services LLC 8 National Grid Energy Management LLC 3 National Grid Energy Services LLC 3 National Grid Energy Trading Services LLC 8 National Grid Engineering & Survey Inc. 8 National Grid Generation LLC 8 National Grid Generation Ventures LLC 8 National Grid Glenwood Energy Center, LLC 3 National Grid IGTS Corp. 8 National Grid Insurance USA Ltd 10 National Grid Islander East Pipeline LLC 3 National Grid LNG GP LLC 3 National Grid LNG LLC 3 National Grid LNG LP LLC 3 National Grid Millennium LLC 3 National Grid NE Holdings 2 LLC 2 National Grid North America Inc. 3 National Grid Partners Inc. 8 National Grid Partners LLC 3 National Grid Port Jefferson Energy Center LLC 3 National Grid Renewables Development, LLC National Grid Renewables E Wind, LLC 5 National Grid Renewables Operations, LLC 3 National Grid Renewables Projects, LLC 5 National Grid Renewables Stutsman, LLC National Grid Renewables, LLC 3 National Grid Services Inc. 3 National Grid US 6 LLC 3,† National Grid US LLC 3 National Grid USA Service Company, Inc. 2 National Grid USA 3 NEES Energy, Inc. 2 New England Electric Transmission Corporation 4 New England Energy Incorporated 2 New England Hydro Finance Company, Inc. (53.704%) 2 New England Hydro-Transmission Corporation (53.704%) 4 New England Hydro-Transmission Electric Company, Inc. (53.704%) 2 New England Power Company 2 Newport America Corporation 11 Newton Solar, LLC NG Renewables Energy Marketing, LLC 3 NG Renewables Energy Services, LLC NGNE LLC 3 NGV Emerald Energy Venture Holdings, LLC 3 NGV OSW Holdings, LLC 3 NGV US Distributed Energy Inc. 3 NGV US Transmission Inc. 3 NGV US, LLC 3 Niagara Mohawk Energy, Inc. 3 Niagara Mohawk Holdings, Inc. 8 Niagara Mohawk Power Corporation 8 Niobrara Wind, LLC NM Properties, Inc. 8 Noble Solar, LLC 12 Nordic VOS, LLC North East Transmission Co., Inc. 3 North Fork Wind, LLC Northeast Renewable Link LLC 3 Opinac North America, Inc. 3 Parklawn Solar, LLC Pennington Solar, LLC Peony Solar, LLC Philadelphia Coke Co., Inc. 3 Pierce County Solar, LLC Pike County Solar, LLC Pipestone Solar, LLC Plum Creek Wind Farm 2, LLC Plum Creek Wind Farm, LLC Port of the Islands North, LLC 8 Portage Solar, LLC Prairie Oasis Solar, LLC Prairie Rose Wind 2, LLC 5 Prosperity Wind Farm 2, LLC Prosperity Wind Farm, LLC Red Rock Solar SD, LLC Red Wolf Solar, LLC Regal Solar 2, LLC Regal Solar, LLC River North Solar, LLC Robertson Solar, LLC Rock Ridge Wind Farm, LLC Rolling Hills Solar, LLC Ross County Solar, LLC 6 Royal Solar 2, LLC Royal Solar, LLC Royerton Solar, LLC Saginaw Bay Solar, LLC Sandstone Creek Solar 2, LLC Sandstone Creek Solar, LLC Sapphire Sky Wind Farm, LLC Sherco Solar 2, LLC 5 Sherco Solar, LLC 5 Silver City Solar, LLC Simpson Solar, LLC Spotlight Solar, LLC Spring Brook Solar, LLC Spring River Solar, LLC Springfield Solar Farm, LLC Stony Brook Wind, LLC Stony Point Solar, LLC Stove Creek Solar, LLC Sturgis Solar, LLC Summit Lake Solar, LLC Sunbeam Solar, LLC Sunrise Solar, LLC Sycamore Creek Solar, LLC Thacker Solar, LLC The Brooklyn Union Gas Company 8 The Narragansett Electric Company 11 Torchlight Solar, LLC 5 Transgas Inc. 2 Tri-City Solar, LLC Uintah Solar, LLC Unbridled Solar, LLC Upper Hudson Development Inc. 8 Valley Solar, LLC Vermont Green Line Devco, LLC (90%) 3 Vibrant Solar, LLC Virgo Community Solar Gardens, LLC 5 Virtue Solar, LLC Vivid Solar, LLC Wallowa Solar, LLC Wayfinder Group, Inc. 2 Wheatfield Solar, LLC White Elm Wind Farm, LLC Wild Springs Solar, LLC 5 Wildcat Ridge Wind Farm, LLC Wildhorse Creek Solar, LLC Willard Solar, LLC Williams County Solar, LLC Wiregrass Solar, LLC Woodlands Solar, LLC Worthington Solar, LLC Yellowhammer Solar, LLC Young County Solar, LLC Incorporated in Australia Registered office: Level 7, 330 Collins Street, Melbourne, VIC 3000, Australia National Grid Australia Pty Limited Incorporated in Canada Registered office: Stewart McKelvey LLP, c/o Charles Reagh, Queen’s Marque, 600-1741 Lower Water Street, Halifax, Nova Scotia, B3J 0J2, Canada KeySpan Energy Development Co. Incorporated in Guernsey Registered office: 1st & 2nd Floors Elizabeth House, Les Ruettes Brayes, St Peter Port, GY1 1EW, Guernsey, Channel Islands WPD Limited (Guernsey) † Registered office: PO Box 155, Mill Court, La Charroterie, St. Peter Port, Guernsey, GY1 4ET, Guernsey, Channel Islands Aztec Insurance Limited Incorporated in Hong Kong Registered office: Level 54, Hopewell Centre, 183 Queen’s Road East, Hong Kong National Grid Hong Kong Limited † Incorporated in the Isle of Man Registered office: Third Floor, St George’s Court, Upper Church Street, Douglas, IM1 1EE, Isle of Man, UK National Grid Insurance Company (Isle of Man) Limited NGT Holding Company (Isle of Man) Limited* † Incorporated in Luxembourg Registered office: 412F, Route d’Esch, L-2086, Luxembourg, Grand Duchy of Luxembourg National Grid Luxembourg SARL Incorporated in the Netherlands Registered office: Westblaak 89, 3012 KG Rotterdam, PO Box 21153, 3001 AD, Rotterdam, Netherlands British Transco International Finance B.V. Incorporated in the Republic of Ireland Registered office: c/o Moore Stephens Nathans, Third Floor, Ulysses House, 23/24 Foley Street, Dublin, D01 W2T2, Ireland National Grid Company (Ireland) Designated Activity Company* 1. Registered office: National Registered Agents, Inc., 160 Greentree Drive, Suite 101, Dover DE 19904, USA. 2. Registered office: Corporation Service Company, 84 State Street, Boston MA 02109, USA. 3. Registered office: Corporation Service Company, 251 Little Falls Drive, Wilmington DE 19808, USA. 4. Registered office: Corporation Service Company, 10 Ferry Street, Suite 313, Concord NH 03301, USA. 5. Registered office: National Grid Renewables Development, LLC, 8400 Normandale Lake Blvd. Suite 1200, Bloomington, MN 55437, USA. 6. Registered office: The Corporation Trust Company, Corporation Trust Center, 1209 Orange Street, Wilmington, Delaware, 19801, USA. 7. Registered office: 60 Mine Lake Court, Suite 200, Raleigh, Wake County, NC 27615, USA. 8. Registered office: Corporation Service Company, 80 State Street, Albany NY 12207, USA. 9. Registered office: National Registered Agents, Inc., 30600 Telegraph Road, Suite 2345, Bingham Farms, MI 48025-5720, USA. 10. Registered office: One MetroTech Center, Brooklyn NY 11201, USA. 11. Registered office: Corporation Service Company, 222 Jefferson Boulevard, Suite 200, Warwick RI 02888, USA. 12. Registered office: National Registered Agents, Inc., 1999 Bryan Street, Dallas, Dallas County TX 75201, USA. * In liquidation. † Entity is tax resident in the United Kingdom. A list of the Group’s joint ventures as at 31 March 2022 is given below. All joint ventures are included in the Group’s financial statements using the equity method of accounting. Principal joint ventures are identified in bold . Incorporated in England and Wales Registered office: 1–3 Strand, London WC2N 5EH, UK (unless stated otherwise in footnotes). BritNed Development Limited (50%)* Joint Radio Company Limited (50%) 1 ** National Places LLP (50%) 2 Nemo Link Limited (50%) NGET/SPT Upgrades Limited (50%) † Incorporated in the US Registered office: Corporation Service Company, 251 Little Falls Drive, Wilmington, DE 19808, USA (unless stated otherwise in footnotes). Bight Wind Holdings, LLC (27.27%) 3 Clean Energy Storage Systems LLC (previously Clean Energy Generation, LLC) (50%) Emerald Energy Venture LLC (51%) Island Park Energy Center, LLC (50%) Islander East Pipeline Company, LLC (50%) 3 LI Energy Storage System, LLC (50%) LI Solar Generation, LLC (50%) Incorporated in France Registered office: 1 Terrasse Bellini, Tour Initiale, TSA 41000 – 9291, IFA2 (50%) A list of the Group’s associates as at 31 March 2022 is given below. Unless otherwise stated, all associates are included in the Group’s financial statements using the equity method of accounting. Principal associates are identified in bold . Incorporated in the US Registered office: Corporation Service Company, 251 Little Falls Drive, Wilmington, DE 19808, USA (unless stated otherwise in footnotes). Clean Line Energy Partners LLC (32%) 3 Connecticut Yankee Atomic Power Company (19.5%) 4 Direct Global Power, Inc. (26%) 3 Energy Impact Fund LP (9.41%) 5 KHB Venture LLC (33.33%) 6 Maine Yankee Atomic Power Company (24%) 7 Millennium Pipeline Company, LLC (26.25%) 3 New York Transco LLC (28.3%) 8 NYSEARCH RMLD, LLC (22.63%) The Hive IV, LLC (28.2%) 3 Yankee Atomic Electric Company (34.5%) 9 Incorporated in Belgium Registered office: Avenue de Cortenbergh 71, 1000 Brussels, Belgium Coreso SA (15.84%) Other investments A list of the Group’s other investments as at 31 March 2022 is given below. Incorporated in England and Wales Registered office: 1 More London Place, London SE1 2AF, UK Energis plc (33.06%)‡ Registered office: Third Floor, Northumberland House, 303–306 High Holborn, London, WC1V 7JZ Electralink Limited (27.04%) 1. Registered office: Friars House, Manor House Drive, Coventry, CV1 2TE, UK. 2. Registered office: 80 Cheapside, London, EC2V 6EE, UK. 3. Registered office: The Corporation Trust Company, Corporation Trust Center, 1209 Orange Street, Wilmington DE 19801, USA. 4. Registered office: Carla Pizzella, 362 Injun Hollow Road, East Hampton CT 06424-3099, USA. 5. Registered office: Harvard Business Services, Inc., 16192 Coastal Highway, Lewes DE 19958, USA. 6. Registered office: De Maximus Inc., 135 Beaver Street, 4th Floor, Waltham MA 02452, USA. 7. Registered office: Joseph D Fay, 321 Old Ferry Road, Wiscasset ME 04578, USA. 8. Registered office: Corporation Service Company, 80 State Street, Albany NY 12207, USA. 9. Registered office: Karen Sucharzewski, 49 Yankee Road, Rowe MA 01367, USA. * National Grid Interconnector Holdings Limited owns 284,500,000 €0.20 C Ordinary shares and one £1.00 Ordinary A share. ** National Grid Gas plc owns all £1.00 A Ordinary shares. † National Grid Electricity Transmission plc owns 50 £1.00 A Ordinary shares. ‡ In administration.
Disclosure of subsidiaries taking advantage of audit exemption under section 479A of Companies Act 2006	The following UK subsidiaries will take advantage of the audit exemption set out within section 479A of the Companies Act 2006 supported by guarantees issued by National Grid plc over their liabilities for the year ended 31 March 2022: Company name Company number NatGrid One Limited 5521240 Natgrid TW1 Limited 7579324 National Grid Holdings Limited 3096772 National Grid International Limited 2537092 National Grid Twelve Limited 4355616 National Grid Twenty Three Limited 6999009 National Grid (US) Holdings Limited 2630496 National Grid (US) Investments 2 Limited 3784528 National Grid (US) Investments 4 Limited 3867128 National Grid (US) Partner 1 Limited 4314432

Sensitivites (Tables)

Sensitivites (Tables)	12 Months Ended
	Mar. 31, 2022
Disclosure of sensitivity analysis for actuarial assumptions [abstract]
Schedule of sensitivity analysis for actuarial assumptions	Derivative financial instruments were used to manage foreign currency risk as follows: 2022 2021 Sterling Euro Dollar Other Total Sterling £m Euro £m Dollar £m Other £m Total £m Cash and cash equivalents 111 — 93 — 204 63 — 94 — 157 Financial investments 1,725 — 1,420 — 3,145 1,215 — 1,127 — 2,342 Borrowings (22,910) (7,052) (14,118) (1,385) (45,465) (12,210) (5,351) (12,660) (999) (31,220) Pre-derivative position (21,074) (7,052) (12,605) (1,385) (42,116) (10,932) (5,351) (11,439) (999) (28,721) Derivative effect (1,378) 6,849 (7,570) 1,406 (693) (826) 5,459 (5,494) 1,036 175 Net debt position (22,452) (203) (20,175) 21 (42,809) (11,758) 108 (16,933) 37 (28,546) The currency exposure on other financial instruments is as follows: 2022 2021 Sterling Euro Dollar Other Total Sterling £m Euro £m Dollar £m Other £m Total £m Trade and other receivables 407 — 1,788 — 2,195 282 — 1,387 — 1,669 Trade and other payables (1,459) — (2,554) — (4,013) (1,207) — (1,878) — (3,085) Other non-current liabilities (90) — (253) — (343) (77) — (288) — (365) The table below sets out the sensitivity analysis for certain areas of estimation uncertainty set out in note 1F. These estimates are those that have a significant risk of resulting in a material adjustment to the carrying values of assets and liabilities in the next year. Note that the sensitivity analysis for the useful economic lives of our gas network assets is included in note 13. 2022 2021 Income Net Income statement £m Net assets £m Pensions and other post-retirement benefit liabilities (pre-tax)¹: UK discount rate change of 0.5%² 12 1,002 4 952 US discount rate change of 0.5%² 16 650 17 730 UK RPI rate change of 0.5%³ 11 733 3 723 UK long-term rate of increase in salaries change of 0.5% 4 88 1 42 US long-term rate of increase in salaries change of 0.5% 3 41 3 42 UK change of one year to life expectancy at age 65 4 4 635 1 612 US change of one year to life expectancy at age 65 3 444 4 429 Assumed US healthcare cost trend rates change of 1% 24 414 26 437 Environmental provision: 10% change in estimated future cash flows 188 188 170 170 1. The changes shown are a change in the annual pension and other post-retirement benefit service charge and change in the defined benefit obligations. 2. A change in the discount rate is likely to occur as a result of changes in bond yields and as such would be expected to be offset to a significant degree by a change in the value of the bond assets held by the plans. In the UK, there would also be a £164 million (2021: £257 million) net assets offset from the buy-in policies, where the accounting value of the buy-in asset is set equal to the associated liabilities. 3. The projected impact resulting from a change in RPI reflects the underlying effect on pensions in payment, pensions in deferment and resultant increases in salary assumptions. The buy-in policies would have a £119 million (2021: £190 million) net assets offset to the above. 4. In the UK, the buy-in policies and the longevity swap entered into would have a £111 million (2021: £183 million) net assets offset to the above. 2022 2021 Income Other equity Income statement £m Other equity reserves £m Financial risk (post-tax): UK RPI change of 0.5%¹ 18 — 25 — UK interest rates change of 0.5% 41 134 12 98 US interest rates change of 0.5% 4 8 6 22 US dollar exchange rate change of 10%² 43 397 44 285 1. Excludes sensitivities to LPI curve. Further details on sensitivities are provided in note 32(g). 2. The other equity reserves impact does not reflect the exchange translation in our US subsidiaries’ net assets. It is estimated this would change by £1,670 million (2021: £1,425 million) in the opposite direction if the dollar exchange rate changed by 10%. Our commodity contract derivatives are sensitive to price risk. Additional sensitivities in respect to commodity price risk and to our derivative fair values are as follows: 2022 2021 Income Net Income statement £m Net assets £m Commodity price risk (post-tax): 10% increase in commodity prices 53 53 20 20 10% decrease in commodity prices (54) (54) (21) (21) Assets and liabilities carried at fair value (post-tax): 10% fair value change in derivative financial instruments¹ (55) (55) 14 14 10% fair value change in commodity contract derivative liabilities 20 20 6 6

Additional disclosures in res_2

Additional disclosures in respect of guaranteed securities (Tables)	12 Months Ended
	Mar. 31, 2022
Separate Financial Statements [Abstract]
Disclosure of condensed balance sheet	Summarised financial information for the year ended 31 March 2022 – IFRS National Grid plc and Niagara Mohawk Power Corporation combined £m Combined statement of financial position Non-current loans to other subsidiaries — Non-current assets 10,068 Current loans to other subsidiaries 28,525 Current assets 2,431 Current loans from other subsidiaries (14,512) Current liabilities (10,276) Non-current loans from other subsidiaries (2,050) Non-current liabilities (8,294) Net assets ¹ 5,892 Equity 5,892 Combined income statement – continuing operations Revenue 2,987 Operating costs (2,358) Operating profit 629 Other income from other subsidiaries 2,500 Other income and costs, including taxation (360) Profit after tax 2,769 1. Excluded from net assets above are investments in other consolidated subsidiaries with a carrying value of £14,440 million.
Disclosure of condensed income statement	Summarised financial information for the year ended 31 March 2022 – IFRS National Grid plc and Niagara Mohawk Power Corporation combined £m Combined statement of financial position Non-current loans to other subsidiaries — Non-current assets 10,068 Current loans to other subsidiaries 28,525 Current assets 2,431 Current loans from other subsidiaries (14,512) Current liabilities (10,276) Non-current loans from other subsidiaries (2,050) Non-current liabilities (8,294) Net assets ¹ 5,892 Equity 5,892 Combined income statement – continuing operations Revenue 2,987 Operating costs (2,358) Operating profit 629 Other income from other subsidiaries 2,500 Other income and costs, including taxation (360) Profit after tax 2,769 1. Excluded from net assets above are investments in other consolidated subsidiaries with a carrying value of £14,440 million.

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Mar. 31, 2022
Business Combinations [Abstract]
Schedule of fair values of the assets and liabilities recognised	The fair values of the assets and liabilities following the finalisation of the purchase price allocation are set out below: IFRS book value at acquisition Fair value adjustments Fair value Non-current assets Property, plant and equipment 14,077 (4,026) 10,051 Other intangible assets 49 1,714 1,763 Pension assets 402 164 566 Other non-current assets 27 — 27 Total non-current assets 14,555 (2,148) 12,407 Current assets Trade and other receivables 268 — 268 Financial and other investments 69 — 69 Cash 44 — 44 Other current assets 42 — 42 Total current assets 423 — 423 Total assets 14,978 (2,148) 12,830 Current liabilities Borrowings (730) — (730) Trade and other payables (531) 48 (483) Other current liabilities (35) — (35) Total current liabilities (1,296) 48 (1,248) Non-current liabilities Borrowings (5,967) (1,589) (7,556) Deferred tax (1,013) 224 (789) Contract liabilities (2,706) 2,706 — Other non-current liabilities (56) (21) (77) Total non-current liabilities (9,742) 1,320 (8,422) Total liabilities (11,038) 1,368 (9,670) Total identifiable net assets 3,940 (780) 3,160 Goodwill 1,254 3,467 4,721 Total consideration transferred 5,194 2,687 7,881 Satisfied by: Cash consideration 7,881 Total consideration transferred 7,881

Basis of preparation and rece_3

Basis of preparation and recent accounting developments - Narratives (Details) £ in Millions	Mar. 27, 2022GBP (£)director	Mar. 17, 2021	Mar. 31, 2022GBP (£)site
Disclosure of subsidiaries [line items]
Number of US Superfund sites | site			3
Prior year adjustment
Disclosure of subsidiaries [line items]
Computer software			£ 34
Narragansett Electric Company
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary sold		100.00%
UK Gas Transmission
Disclosure of subsidiaries [line items]
Number of aquirer's directors that we can appoint | director	2
Total number of directors | director	7
UK Gas Transmission | Forecast
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary sold	100.00%
Cash consideration received	£ 4,200
Portion of consideration received consisting of shareholding in acquirer	40.00%
Fixed interest rate bonds
Disclosure of subsidiaries [line items]
Notional amount			£ 4,200

Segmental analysis - Narrative

Segmental analysis - Narrative (Details)	Mar. 31, 2022segmentbusiness_unit
Disclosure of operating segments [abstract]
Number of operating business units | business_unit	6
Number of reportable operating segments | segment	5

Segmental analysis - Schedule o

Segmental analysis - Schedule of revenue by operating segments (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Disclosure of operating segments [line items]
Revenue	£ 18,449	£ 13,665	[1]	£ 13,360	[2]
UK
Disclosure of operating segments [line items]
Revenue	7,803	4,368		4,102
US
Disclosure of operating segments [line items]
Revenue	10,646	9,297		9,258
Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue		13,665		13,360
UK Electricity Transmission
Disclosure of operating segments [line items]
Revenue	2,028	1,964		1,978
UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	2,028	1,964		1,978
UK Electricity Distribution
Disclosure of operating segments [line items]
Revenue	1,468	0		0
UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	1,468	0		0
UK Electricity System Operator
Disclosure of operating segments [line items]
Revenue	3,437	2,018		1,716
UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	3,437	2,018		1,716
New England
Disclosure of operating segments [line items]
Revenue	4,550	4,214		4,235
New England | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	4,550	4,214		4,235
New York
Disclosure of operating segments [line items]
Revenue	5,561	4,605		4,601
New York | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	5,561	4,605		4,601
NGV and Other
Disclosure of operating segments [line items]
Revenue	1,405	864		830
NGV and Other | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	1,405	864		830
Operating segments | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	18,488	13,675		13,372
Operating segments | UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	2,035	1,974		1,986
Operating segments | UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	1,482	0		0
Operating segments | UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	3,455	2,018		1,716
Operating segments | New England | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	4,550	4,214		4,235
Operating segments | New York | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	5,561	4,605		4,601
Operating segments | NGV and Other | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	1,405	864		834
Sales between segments | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	(39)	(10)		(12)
Sales between segments | UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	(7)	(10)		(8)
Sales between segments | UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	(14)	0		0
Sales between segments | UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	(18)	0		0
Sales between segments | New England | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	0	0		0
Sales between segments | New York | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	0	0		0
Sales between segments | NGV and Other | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Revenue	£ 0	£ 0		£ (4)
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Segmental analysis - Schedule_2

Segmental analysis - Schedule of operating profit by operating segments (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Disclosure of operating segments [line items]
Total operating profit from continuing operations	£ 4,371	£ 2,401	[1]	£ 2,279	[2]
Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	3,813	2,427		2,804
Exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	558	(26)		(525)
UK
Disclosure of operating segments [line items]
Total operating profit from continuing operations	2,458	1,056		1,414
UK | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	2,234	1,113		1,422
UK | Exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	224	(57)		(8)
US
Disclosure of operating segments [line items]
Total operating profit from continuing operations	1,913	1,345		865
US | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	1,579	1,314		1,382
US | Exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	334	31		(517)
Operating segments | UK Electricity Transmission
Disclosure of operating segments [line items]
Total operating profit from continuing operations	1,055	1,080		1,104
Operating segments | UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	1,067	1,094		1,109
Operating segments | UK Electricity Transmission | Exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	(12)	(14)		(5)
Operating segments | UK Electricity Distribution
Disclosure of operating segments [line items]
Total operating profit from continuing operations	909	0		0
Operating segments | UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	909	0		0
Operating segments | UK Electricity Distribution | Exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	0	0		0
Operating segments | UK Electricity System Operator
Disclosure of operating segments [line items]
Total operating profit from continuing operations	5	(53)		212
Operating segments | UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	7	(60)		211
Operating segments | UK Electricity System Operator | Exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	(2)	7		1
Operating segments | New England
Disclosure of operating segments [line items]
Total operating profit from continuing operations	764	614		470
Operating segments | New England | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	743	611		523
Operating segments | New England | Exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	21	3		(53)
Operating segments | New York
Disclosure of operating segments [line items]
Total operating profit from continuing operations	1,095	695		370
Operating segments | New York | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	780	665		835
Operating segments | New York | Exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	315	30		(465)
Operating segments | NGV and Other
Disclosure of operating segments [line items]
Total operating profit from continuing operations	543	65		123
Operating segments | NGV and Other | Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	307	117		126
Operating segments | NGV and Other | Exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	£ 236	£ (52)		£ (3)
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Segmental analysis - Schedule_3

Segmental analysis - Schedule of reconciliation of total operating profit to profit before tax from continuing operations (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Disclosure of operating segments [line items]
Total operating profit from continuing operations	£ 4,371	£ 2,401	[1]	£ 2,279	[2]
Share of post-tax results of joint ventures and associates	92	58	[1]	87	[3]
Finance income	50	58	[1]	54	[3]
Finance costs	(1,072)	(853)	[1]	(1,020)	[3]
Profit/(loss) before tax	3,441	1,664	[1]	1,400	[3]
Before exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	3,813	2,427		2,804
Share of post-tax results of joint ventures and associates	148	66		88
Finance income	65	35		70
Finance costs	(1,146)	(900)		(999)
Profit/(loss) before tax	2,880	1,628		1,963
Exceptional items and remeasurements
Disclosure of operating segments [line items]
Total operating profit from continuing operations	558	(26)		(525)
Share of post-tax results of joint ventures and associates	(56)	(8)		(1)
Finance income	(15)	23		(16)
Finance costs	74	47		(21)
Profit/(loss) before tax	£ 561	£ 36		£ (563)
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[3]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Segmental analysis - Schedule_4

Segmental analysis - Schedule of capital expenditure by operating segments (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	£ 60,804	£ 43,761	£ 46,336
Capital expenditure	6,185	4,727	4,792
Depreciation, amortisation and impairment	(1,830)	(1,485)	(1,435)
Property, plant and equipment
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	57,532	42,424	45,160
Capital expenditure	5,714	4,335	4,465
Depreciation, amortisation and impairment	(1,544)	(1,317)	(1,286)
Non-current intangible assets
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	3,272	1,337	1,176
Capital expenditure	471	392	327
Depreciation, amortisation and impairment	(286)	(168)	(149)
UK
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	30,131	16,627	15,706
Capital expenditure	2,546	1,504	1,560
Depreciation, amortisation and impairment	(879)	(596)	(579)
US
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	30,673	27,134	30,630
Capital expenditure	3,639	3,223	3,232
Depreciation, amortisation and impairment	(951)	(889)	(856)
Operating segments | UK Electricity Transmission
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	14,678	14,000	13,463
Capital expenditure	1,195	984	951
Depreciation, amortisation and impairment	(508)	(460)	(431)
Operating segments | UK Electricity Distribution
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	12,522	0	0
Capital expenditure	899	0	0
Depreciation, amortisation and impairment	(158)	0	0
Operating segments | UK Electricity System Operator
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	404	379	336
Capital expenditure	108	88	92
Depreciation, amortisation and impairment	(83)	(47)	(38)
Operating segments | New England
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	11,485	10,165	13,127
Capital expenditure	1,561	1,437	1,365
Depreciation, amortisation and impairment	(364)	(389)	(373)
Operating segments | New York
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	18,676	16,467	16,920
Capital expenditure	1,960	1,738	1,822
Depreciation, amortisation and impairment	(537)	(453)	(436)
Operating segments | NGV and Other
Disclosure of operating segments [line items]
Net book value of property, plant and equipment and other intangible assets	3,039	2,750	2,490
Capital expenditure	462	480	562
Depreciation, amortisation and impairment	£ (180)	£ (136)	£ (157)

Revenue - Disclosure of disaggr

Revenue - Disclosure of disaggregation of revenue by primary geographical market and major service lines (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		£ 13,084		£ 12,787
Total other revenue		581		573
Total revenue from continuing operations	£ 18,449	13,665	[1]	13,360	[2]
Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	17,714
Total other revenue	735
Total revenue from continuing operations		13,665		13,360
UK Electricity Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		1,942		1,967
Total other revenue		22		11
Total revenue from continuing operations	2,028	1,964		1,978
UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	2,018
Total other revenue	10
Total revenue from continuing operations	2,028	1,964		1,978
UK Electricity Distribution
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Total other revenue		0		0
Total revenue from continuing operations	1,468	0		0
UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	1,464
Total other revenue	4
Total revenue from continuing operations	1,468	0		0
UK Electricity System Operator
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		2,015		1,704
Total other revenue		3		12
Total revenue from continuing operations	3,437	2,018		1,716
UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	3,437
Total other revenue	0
Total revenue from continuing operations	3,437	2,018		1,716
New England
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		4,173		4,197
Total other revenue		41		38
Total revenue from continuing operations	4,550	4,214		4,235
New England | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	4,496
Total other revenue	54
Total revenue from continuing operations	4,550	4,214		4,235
New York
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		4,562		4,559
Total other revenue		43		42
Total revenue from continuing operations	5,561	4,605		4,601
New York | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	5,525
Total other revenue	36
Total revenue from continuing operations	5,561	4,605		4,601
NGV and Other
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		392		360
Total other revenue		472		470
Total revenue from continuing operations	1,405	864		830
NGV and Other | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	774
Total other revenue	631
Total revenue from continuing operations	1,405	864		830
UK
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		4,284		3,993
Total other revenue		84		109
Total revenue from continuing operations	7,803	4,368		4,102
UK | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	7,565
Total other revenue	238
UK | UK Electricity Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		1,942		1,967
Total other revenue		22		11
UK | UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	2,018
Total other revenue	10
UK | UK Electricity Distribution
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Total other revenue		0		0
UK | UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	1,464
Total other revenue	4
UK | UK Electricity System Operator
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		2,015		1,704
Total other revenue		3		12
UK | UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	3,437
Total other revenue	0
UK | New England
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Total other revenue		0		0
UK | New England | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
Total other revenue	0
UK | New York
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Total other revenue		0		0
UK | New York | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
Total other revenue	0
UK | NGV and Other
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		327		322
Total other revenue		59		86
UK | NGV and Other | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	646
Total other revenue	224
US
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		8,800		8,794
Total other revenue		497		464
Total revenue from continuing operations	10,646	9,297		9,258
US | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	10,149
Total other revenue	497
US | UK Electricity Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Total other revenue		0		0
US | UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
Total other revenue	0
US | UK Electricity Distribution
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Total other revenue		0		0
US | UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
Total other revenue	0
US | UK Electricity System Operator
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Total other revenue		0		0
US | UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
Total other revenue	0
US | New England
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		4,173		4,197
Total other revenue		41		38
US | New England | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	4,496
Total other revenue	54
US | New York
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		4,562		4,559
Total other revenue		43		42
US | New York | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	5,525
Total other revenue	36
US | NGV and Other
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		65		38
Total other revenue		413		384
US | NGV and Other | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	128
Total other revenue	407
Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		2,594		2,632
Transmission | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	3,067
Transmission | UK Electricity Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		1,875		1,898
Transmission | UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	1,983
Transmission | UK Electricity Distribution
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Transmission | UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
Transmission | UK Electricity System Operator
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Transmission | UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
Transmission | New England
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		74		77
Transmission | New England | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	52
Transmission | New York
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		329		348
Transmission | New York | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	405
Transmission | NGV and Other
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		316		309
Transmission | NGV and Other | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	627
Distribution
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		8,317		8,319
Distribution | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	10,919
Distribution | UK Electricity Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Distribution | UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
Distribution | UK Electricity Distribution
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Distribution | UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	1,375
Distribution | UK Electricity System Operator
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Distribution | UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
Distribution | New England
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		4,091		4,114
Distribution | New England | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	4,434
Distribution | New York
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		4,226		4,205
Distribution | New York | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	5,110
Distribution | NGV and Other
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Distribution | NGV and Other | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
System Operator
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		2,076		1,610
System Operator | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	3,418
System Operator | UK Electricity Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
System Operator | UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
System Operator | UK Electricity Distribution
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
System Operator | UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
System Operator | UK Electricity System Operator
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		2,076		1,610
System Operator | UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	3,418
System Operator | New England
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
System Operator | New England | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
System Operator | New York
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
System Operator | New York | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
System Operator | NGV and Other
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
System Operator | NGV and Other | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	0
Other
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		97		226
Total other revenue		205		204
Other | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	310
Total other revenue	362
Other | UK Electricity Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		67		69
Total other revenue		22		11
Other | UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	35
Total other revenue	10
Other | UK Electricity Distribution
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		0		0
Total other revenue		0		0
Other | UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	89
Total other revenue	4
Other | UK Electricity System Operator
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		(61)		94
Total other revenue		3		12
Other | UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	19
Total other revenue	0
Other | New England
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		8		6
Total other revenue		41		38
Other | New England | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	10
Total other revenue	54
Other | New York
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		7		6
Total other revenue		43		42
Other | New York | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	10
Total other revenue	36
Other | NGV and Other
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue		76		51
Total other revenue		96		101
Other | NGV and Other | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total IFRS 15 revenue	147
Total other revenue	258
Generation
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue		376		369
Generation | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue	373
Generation | UK Electricity Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue		0		0
Generation | UK Electricity Transmission | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue	0
Generation | UK Electricity Distribution
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue		0		0
Generation | UK Electricity Distribution | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue	0
Generation | UK Electricity System Operator
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue		0		0
Generation | UK Electricity System Operator | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue	0
Generation | New England
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue		0		0
Generation | New England | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue	0
Generation | New York
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue		0		0
Generation | New York | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue	0
Generation | NGV and Other
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue		£ 376		£ 369
Generation | NGV and Other | Before exceptional items and remeasurements
Disclosure of disaggregation of revenue from contracts with customers [line items]
Total other revenue	£ 373
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Revenue - Narrative (Details)

Revenue - Narrative (Details) - GBP (£) £ in Millions	Mar. 15, 2022	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of disaggregation of revenue from contracts with customers [line items]
Contract liabilities		£ 1,472	£ 1,160	£ 1,158
Future revenues in relation to unfulfilled performance obligations		£ 5,200	4,800	3,100
Remaining performance obligation, expected timing of satisfaction, period		3 years
Revenue from performance obligations satisfied or partially satisfied in previous periods		£ 0	0	0
National Grid Grain LNG Limited
Disclosure of disaggregation of revenue from contracts with customers [line items]
Future revenues in relation to unfulfilled performance obligations		3,000	3,000	1,500
UK Gas Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Contract liabilities			136	136
UK Electricity Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Future revenues in relation to unfulfilled performance obligations		£ 1,700	£ 1,600	£ 1,500
Remaining performance obligation, expected timing of satisfaction, period		25 years
Connections | Weighted average
Disclosure of disaggregation of revenue from contracts with customers [line items]
Asset useful life		31 years
Connections | UK Electricity Transmission
Disclosure of disaggregation of revenue from contracts with customers [line items]
Asset useful life		40 years
Connections | UK Electricity Distribution
Disclosure of disaggregation of revenue from contracts with customers [line items]
Asset useful life		69 years
Connections | New England
Disclosure of disaggregation of revenue from contracts with customers [line items]
Asset useful life		51 years
Connections | New York
Disclosure of disaggregation of revenue from contracts with customers [line items]
Asset useful life		48 years
St William Homes LLP
Disclosure of disaggregation of revenue from contracts with customers [line items]
Proportion of ownership interest disposed	50.00%

Other operating income and co_3

Other operating income and costs - Analysis of expenses by nature (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Operating Costs [Line Items]
Depreciation, amortisation and impairment	£ 1,830	£ 1,485		£ 1,435
Payroll costs	1,794	1,638		1,558
Purchases of electricity	1,280	1,130		1,403
Purchases of gas	1,666	1,250		1,316
Property and other taxes	1,202	1,105		1,100
UK Electricity Balancing costs	3,152	1,875		1,317
Other	3,215	2,456		2,718
Other operating (income)/costs	13,911	10,939	[1]	10,847	[2]
Provision for bad and doubtful debts	167	325	[1]	234	[2]
Total operating costs from continuing operations	14,078	11,264		11,081
Operating costs from continuing operations include:
Inventory consumed	436	312		315
Research and development expenditure	11	12		9
St William Homes LLP
Operating Costs [Line Items]
(Gain) on disposal of St William Homes LLP (note 5)	£ (228)	£ 0		£ 0
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Other operating income and co_4

Other operating income and costs - Payroll costs (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Analysis of income and expense [abstract]
Wages and salaries	£ 2,563	£ 2,170	£ 2,081
Social security costs	201	156	152
Defined contribution scheme costs	81	67	62
Defined benefit pension costs	185	126	125
Share-based payments	38	23	16
Severance costs (excluding pension costs)	5	9	1
Payroll costs including capitalised costs	3,073	2,551	2,437
Less: payroll costs capitalised	(1,279)	(913)	(879)
Total payroll costs from continuing operations	1,794	1,638	1,558
US other post retirement benefit costs	£ 39	£ 43	£ 45

Other operating income and co_5

Other operating income and costs - Number of employees (Details) - employee	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of operating segments [line items]
Number of employees, year end	29,292	21,494	20,933
Average number of employees	28,707	21,154	20,774
UK
Disclosure of operating segments [line items]
Number of employees, year end	11,960	4,468	4,185
Average number of employees	11,393	4,333	4,095
US
Disclosure of operating segments [line items]
Number of employees, year end	17,332	17,026	16,748
Average number of employees	17,314	16,821	16,679

Other operating income and co_6

Other operating income and costs - Key management personnel (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Analysis of income and expense [abstract]
Short-term employee benefits	£ 7	£ 7	£ 7
Compensation for loss of office	0	0	1
Post-employment benefits	1	1	1
Share-based payments	5	4	3
Total key management compensation	£ 13	£ 12	£ 12

Other operating income and co_7

Other operating income and costs - Auditors remuneration (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Audit fees payable to the Parent Company’s auditors and their associates in respect of:
Audit of the Parent Company’s individual and consolidated financial statements	£ 2.7	£ 2.5	£ 1.9
The auditing of accounts of any associate of the Company	8.9	8.1	8.7
Other services supplied	7.3	6.4	6.3
Audit fees payable to the Parent Company’s auditors and their associates	18.9	17	16.9
All other fees:
Other assurance services	0.9	0.8	0.6
Other non-audit services not covered above	0.1	2	0.5
Total other services	1	2.8	1.1
Total auditors’ remuneration	19.9	£ 19.8	£ 18
Tax compliance services	0
Tax advisory services	£ 0

Exceptional items and remeasu_3

Exceptional items and remeasurements (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Included within operating profit
Release of St William Homes LLP deferred income	£ 18,449	£ 13,665	[1]	£ 13,360	[2]
Operating profit	4,371	2,401	[1]	2,279	[3]
Included within finance income and costs
Finance income and costs	(1,022)	(795)		(966)
Included within share of post-tax results of joint ventures and associates
Profit/(loss) before tax	3,441	1,664	[1]	1,400	[2]
Included within tax
Tax on exceptional items and remeasurements	(1,258)	(360)	[1]	(370)	[2]
Analysis of total exceptional items and remeasurements after tax
Profit after tax from continuing operations	2,183	1,304	[4]	1,030	[2]
St William Homes LLP
Included within operating profit
Net gain on disposal of St William Homes LLP	228	0		0
Exceptional items and remeasurements
Included within operating profit
Operating profit	558	(26)		(525)
Included within share of post-tax results of joint ventures and associates
Profit/(loss) before tax	561	36		(563)
Included within tax
Tax on exceptional items and remeasurements	(589)	(26)		(8)
Analysis of total exceptional items and remeasurements after tax
Profit after tax from continuing operations	(28)	10		(571)
Exceptional items
Included within operating profit
New operating model implementation costs and cost efficiency programme	(66)	(50)		0
Transaction and separation costs	(223)	(24)		0
Environmental insurance recovery	38	0		0
Changes in environmental provisions	0	14		(400)
Operating profit	166	(60)		(400)
Included within tax
Tax on exceptional items and remeasurements	(28)	8		103
Analysis of total exceptional items and remeasurements after tax
Profit after tax from continuing operations	(320)	(52)		(445)
Exceptional items | UK
Included within tax
Deferred tax charge arising as a result of UK tax rate change	(458)	0		(148)
Exceptional items | St William Homes LLP
Included within operating profit
Release of St William Homes LLP deferred income	189	0		0
Net gain on disposal of St William Homes LLP	228	0		0
Remeasurements
Included within finance income and costs
Net gains/(losses) on financing derivatives	74	47		(21)
Net (losses)/gains on financial assets at fair value through profit and loss	(15)	23		(16)
Finance income and costs	59	70		(37)
Included within share of post-tax results of joint ventures and associates
Remeasurements – net losses on financial instruments	(56)	(8)		(1)
Included within tax
Tax on exceptional items and remeasurements	(103)	(34)		37
Analysis of total exceptional items and remeasurements after tax
Profit after tax from continuing operations	292	62		(126)
Remeasurements | Commodity contract derivatives
Included within operating profit
Operating profit	£ 392	£ 34		£ (125)
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[3]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[4]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Exceptional items and remeasu_4

Exceptional items and remeasurements - Narrative (Details) £ in Millions	Mar. 15, 2022GBP (£)	Mar. 31, 2022GBP (£)	Mar. 31, 2021GBP (£)business_unit		Mar. 31, 2020GBP (£)		Mar. 31, 2017GBP (£)
Disclosure of other provisions [line items]
Release of St William Homes LLP deferred income		£ 18,449	£ 13,665	[1]	£ 13,360	[2]
Other provisions		2,539	£ 2,227		2,654
Number of business units | business_unit			6
Increase in provisions		423	£ 146
US
Disclosure of other provisions [line items]
Release of St William Homes LLP deferred income		10,646	9,297		9,258
Environmental
Disclosure of other provisions [line items]
Other provisions		1,877	1,700		£ 2,071
Increase in provisions		158	26
Real discount rate (in percent)					0.50%
Weighted average duration of cash flows					10 years
Environmental | US
Disclosure of other provisions [line items]
Other provisions		£ 1,725	£ 1,533
Real discount rate (in percent)		0.50%	0.50%
Weighted average duration of cash flows		11 years
Environmental | UK
Disclosure of other provisions [line items]
Other provisions		£ 152	£ 167
Real discount rate (in percent)		0.50%	0.50%
St William Homes LLP
Disclosure of other provisions [line items]
Net gain on disposal of St William Homes LLP		£ 228	£ 0		£ 0
Proportion of ownership interest disposed	50.00%
Cash consideration received	£ 413
Exceptional items
Disclosure of other provisions [line items]
New operating model implementation costs and cost efficiency programme		66	50		0
Cash outflow for new operating model implementation costs and cost efficiency programme		48	33
Transaction and separation costs		(223)	(24)		0
Cash outflow for transaction and separation costs		196	14
Changes in environmental provisions		0	14		(400)
Deferred tax expense arising from reduction in UK tax rate							£ 94
Exceptional items | UK
Disclosure of other provisions [line items]
Deferred tax charge arising as a result of UK tax rate change		458			148
Exceptional items | St William Homes LLP
Disclosure of other provisions [line items]
Net gain on disposal of St William Homes LLP		228	0		0
Release of St William Homes LLP deferred income		£ 189	£ 0		0
Exceptional items, change in estimate of total cost and cost sharing | Environmental
Disclosure of other provisions [line items]
Increase in provisions					326
Exceptional items, impact of change in the real discount rate | Environmental
Disclosure of other provisions [line items]
Increase in provisions					74
Exceptional items, impact of change in the real discount rate | Environmental | US
Disclosure of other provisions [line items]
Increase in provisions					66
Exceptional items, impact of change in the real discount rate | Environmental | UK
Disclosure of other provisions [line items]
Increase in provisions					£ 8
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Finance income and costs (Detai

Finance income and costs (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Interest income on financial instruments:
Finance income	£ 50	£ 58	[1]	£ 54	[2]
Interest expense on financial liabilities held at amortised cost:
Finance costs	(1,072)	(853)	[1]	(1,020)	[2]
Net gains/(losses) on financing derivatives
Finance income and costs	(1,022)	(795)		(966)
Amount of accretion on inflation linked liabilities	241	46		85
Before exceptional items and remeasurements
Interest income on financial instruments:
Bank deposits and other financial assets	32	33		48
Dividends received on equities held at fair value through other comprehensive income (FVOCI)	3	2		2
Other income	30	0		20
Finance income	65	35		70
Finance costs
Net interest on pensions and other post-retirement benefit obligations	0	(51)		(34)
Interest expense on financial liabilities held at amortised cost:
Bank loans and overdrafts	(216)	(53)		(46)
Other borrowings	(961)	(741)		(846)
Interest on derivatives	(59)	(47)		(92)
Unwinding of discount on provisions	(73)	(77)		(75)
Other interest	11	(51)		(8)
Less: interest capitalised	152	120		102
Finance costs	£ (1,146)	£ (900)		£ (999)
Net gains/(losses) on financing derivatives
Capitalisation rate of borrowing costs eligible for capitalisation	3.20%	3.10%		3.60%
Tax relief on capitalised interest	£ 16	£ 11		£ 15
Remeasurements
Interest income on financial instruments:
Finance income	(15)	23		(16)
Interest expense on financial liabilities held at amortised cost:
Finance costs	(74)	(47)		21
Remeasurements – Finance income
Net gains/(losses) on FVTPL financial assets	(15)	23		(16)
Net gains/(losses) on financing derivatives
Derivatives designated as hedges for hedge accounting	45	30		(14)
Derivatives not designated as hedges for hedge accounting	29	17		(7)
Finance income and costs	59	70		(37)
Net finance costs from continuing operations	£ 110	£ 73		£ 114
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Tax - Tax charges (Details)

Tax - Tax charges (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Current tax:
Total current tax from continuing operations	£ 226	£ 160		£ 94
Deferred tax:
Total deferred tax from continuing operations	1,032	200		276
Total tax charge from continuing operations	1,258	360	[1]	370	[2]
UK
Current tax:
Corporation tax	255	157		132
Corporate tax adjustment in respect of prior years	(9)	15		5
Total current tax from continuing operations	246	172		137
Deferred tax:
Deferred tax	605	39		207
Deferred tax adjustment in respect of prior years	(5)	(20)		(4)
Total deferred tax from continuing operations	600	19		203
Overseas
Current tax:
Corporation tax	6	3		(2)
Corporate tax adjustment in respect of prior years	(26)	(15)		(41)
Total current tax from continuing operations	(20)	(12)		(43)
Deferred tax:
Deferred tax	425	174		64
Deferred tax adjustment in respect of prior years	7	7		9
Total deferred tax from continuing operations	£ 432	£ 181		£ 73
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Tax - Tax charged_(credited) to

Tax - Tax charged/(credited) to the consolidated statement of comprehensive income and equity (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Current tax:
Cash flow hedges, cost of hedging and own credit reserve	£ 0	£ 0	£ 0
Deferred tax:
Investments at fair value through other comprehensive income	0	12	(1)
Cash flow hedges, cost of hedging and own credit reserve	(12)	6	(38)
Remeasurements of pension assets and post-retirement benefit obligations	493	462	(226)
Share-based payments	(4)	1	(2)
Tax charged/(credited) to other comprehensive income and equity	477	481	(267)
Total tax recognised in the statements of comprehensive income from continuing operations	481	480	(265)
Total tax relating to share-based payments recognised directly in equity from continuing operations	£ (4)	£ 1	£ (2)

Tax - Effective tax rate reconc

Tax - Effective tax rate reconciliation (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Disclosure Of Income Taxes [Line Items]
Profit before tax	£ 3,441	£ 1,664	[1]	£ 1,400	[2]
Profit before tax from continuing operations multiplied by UK corporation tax rate of 19% (2021: 19%; 2020: 19%)	654	316		266
Adjustments in respect of prior years	(33)	(12)		(31)
Expenses not deductible for tax purposes	47	29		24
Non-taxable income	(49)	(7)		(18)
Adjustment in respect of foreign tax rates	170	42		18
Adjustment in respect of post-tax profits of joint ventures and associates included within profit before tax	(17)	(12)		(17)
Other	(15)	4		(20)
Total tax charge from continuing operations	£ 1,258	£ 360	[1]	£ 370	[2]
Effective tax rate – continuing operations	36.60%	21.60%		26.40%
Before exceptional items and remeasurements
Disclosure Of Income Taxes [Line Items]
Profit before tax	£ 2,880	£ 1,628		£ 1,963
Exceptional items and remeasurements
Disclosure Of Income Taxes [Line Items]
Profit before tax	561	36		(563)
Total tax charge from continuing operations	589	26		8
UK
Disclosure Of Income Taxes [Line Items]
Deferred tax impact of change in UK tax rate	£ 501	£ 0		£ 148
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Tax - Tax included within the s

Tax - Tax included within the statement of financial position (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Reconciliation of changes in deferred tax liability (asset) [abstract]
Deferred tax liability (asset) beginning of period	£ 4,815	£ 4,446
Exchange adjustments and other	163	(268)
Charged/(credited) to income statement	1,230	215
Charged/(credited) to other comprehensive income and equity	571	422
Reclassification to held for sale (note 10)	(803)
Acquisition of WPD (note 37)	789
Deferred tax liability (asset) end of period	6,765	4,815
Regulatory licenses
Reconciliation of changes in deferred tax liability (asset) [abstract]
Deferred tax liability (asset) beginning of period	0	0
Exchange adjustments and other	0	0
Charged/(credited) to income statement	0	0
Charged/(credited) to other comprehensive income and equity	0	0
Reclassification to held for sale (note 10)	0
Acquisition of WPD (note 37)	429
Deferred tax liability (asset) end of period	429	0
Accelerated tax depreciation
Reconciliation of changes in deferred tax liability (asset) [abstract]
Deferred tax liability (asset) beginning of period	6,434	6,562
Exchange adjustments and other	247	(501)
Charged/(credited) to income statement	1,050	373
Charged/(credited) to other comprehensive income and equity	0	0
Reclassification to held for sale (note 10)	(643)
Acquisition of WPD (note 37)	622
Deferred tax liability (asset) end of period	7,710	6,434
Share- based payments
Reconciliation of changes in deferred tax liability (asset) [abstract]
Deferred tax liability (asset) beginning of period	(42)	(48)
Exchange adjustments and other	(1)	4
Charged/(credited) to income statement	26	0
Charged/(credited) to other comprehensive income and equity	(6)	2
Reclassification to held for sale (note 10)	5
Acquisition of WPD (note 37)	0
Deferred tax liability (asset) end of period	(18)	(42)
Pensions and other post- retirement benefits
Reconciliation of changes in deferred tax liability (asset) [abstract]
Deferred tax liability (asset) beginning of period	93	(360)
Exchange adjustments and other	1	51
Charged/(credited) to income statement	118	(12)
Charged/(credited) to other comprehensive income and equity	587	414
Reclassification to held for sale (note 10)	(166)
Acquisition of WPD (note 37)	142
Deferred tax liability (asset) end of period	775	93
Financial instruments
Reconciliation of changes in deferred tax liability (asset) [abstract]
Deferred tax liability (asset) beginning of period	(44)	(55)
Exchange adjustments and other	1	4
Charged/(credited) to income statement	153	1
Charged/(credited) to other comprehensive income and equity	(10)	6
Reclassification to held for sale (note 10)	2
Acquisition of WPD (note 37)	(403)
Deferred tax liability (asset) end of period	(301)	(44)
Other net temporary differences
Reconciliation of changes in deferred tax liability (asset) [abstract]
Deferred tax liability (asset) beginning of period	(1,626)	(1,653)
Exchange adjustments and other	(85)	174
Charged/(credited) to income statement	(117)	(147)
Charged/(credited) to other comprehensive income and equity	0	0
Reclassification to held for sale (note 10)	(1)
Acquisition of WPD (note 37)	(1)
Deferred tax liability (asset) end of period	(1,830)	(1,626)
Net operating losses
Reconciliation of changes in deferred tax liability (asset) [abstract]
Deferred tax liability (asset) beginning of period	(455)
Deferred tax liability (asset) end of period	(428)	(455)
Environmental provisions
Reconciliation of changes in deferred tax liability (asset) [abstract]
Deferred tax liability (asset) beginning of period	(453)
Deferred tax liability (asset) end of period	(511)	(453)
Allowance for credit losses
Reconciliation of changes in deferred tax liability (asset) [abstract]
Deferred tax liability (asset) beginning of period	(184)
Deferred tax liability (asset) end of period	£ (201)	£ (184)

Tax - Narrative (Details)

Tax - Narrative (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure Of Income Taxes [Line Items]
Net deferred tax liabilities	£ 6,765	£ 4,815	£ 4,446
Deferred tax assets	428	455
Net operating losses
Disclosure Of Income Taxes [Line Items]
Net deferred tax liabilities	(428)	£ (455)
Deferred tax assets	418
Capital losses
Disclosure Of Income Taxes [Line Items]
Deferred tax assets	£ 10

Tax - Deferred tax assets not r

Tax - Deferred tax assets not recognised (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Capital losses
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax assets not recognised	£ 2,363	£ 1,620
Non-trade deficits
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax assets not recognised	1	1
Trading losses
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred tax assets not recognised	£ 7	£ 7

Earnings per share (EPS) - Sche

Earnings per share (EPS) - Schedule of Earnings Per Share (Details) - GBP (£) £ / shares in Units, £ in Millions, shares in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Basic EPS
Basic earnings from continuing operations	£ 2,182	£ 1,303		£ 1,029
Basic earnings from discontinued operations	171	337		235
Basic total earnings	£ 2,353	£ 1,640		£ 1,264
Basic EPS (continuing) (in GBP per share)	£ 0.606	£ 0.370	[1]	£ 0.297	[2]
Basic EPS (discontinuing) (in GBP per share)	0.048	0.096		0.068
Total basic earnings per share (in GBP per share)	£ 0.654	£ 0.466	[1]	£ 0.365	[2]
Weighted average number of shares – basic (in shares)	3,599	3,523		3,461
Diluted EPS
Diluted earnings from continuing operations	£ 2,182	£ 1,303		£ 1,029
Diluted earnings from discontinued operations	171	337		235
Diluted total earnings	£ 2,353	£ 1,640		£ 1,264
Diluted EPS (continuing) (in GBP per share)	£ 0.603	£ 0.368	[1]	£ 0.296	[2]
Diluted EPS (discontinuing) (in GBP per share)	0.047	0.095		0.067
Diluted EPS (in GBP per share)	£ 0.650	£ 0.463	[1]	£ 0.363	[2]
Weighted average number of shares – diluted (in shares)	3,616	3,540		3,478
Reconciliation of basic to diluted average number of shares
Weighted average number of shares – basic (in shares)	3,599	3,523		3,461
Effect of dilutive potential ordinary shares – employee share plans (in shares)	17	17		17
Weighted average number of shares – diluted (in shares)	3,616	3,540		3,478
Before exceptional items and remeasurements
Basic EPS
Basic earnings from continuing operations	£ 2,210	£ 1,293		£ 1,600
Basic earnings from discontinued operations	344	340		317
Basic total earnings	£ 2,554	£ 1,633		£ 1,917
Basic EPS (continuing) (in GBP per share)	£ 0.614	£ 0.367		£ 0.462
Basic EPS (discontinuing) (in GBP per share)	0.096	0.097		0.092
Total basic earnings per share (in GBP per share)	£ 0.710	£ 0.464		£ 0.554
Diluted EPS
Diluted earnings from continuing operations	£ 2,210	£ 1,293		£ 1,600
Diluted earnings from discontinued operations	344	340		317
Diluted total earnings	£ 2,554	£ 1,633		£ 1,917
Diluted EPS (continuing) (in GBP per share)	£ 0.611	£ 0.365		£ 0.460
Diluted EPS (discontinuing) (in GBP per share)	0.095	0.096		0.091
Diluted EPS (in GBP per share)	£ 0.706	£ 0.461		£ 0.551
Exceptional items and remeasurements
Basic EPS
Basic earnings from continuing operations	£ (28)	£ 10		£ (571)
Basic earnings from discontinued operations	(173)	(3)		(82)
Basic total earnings	£ (201)	£ 7		£ (653)
Basic EPS (continuing) (in GBP per share)	£ (0.008)	£ 0.003		£ (0.165)
Basic EPS (discontinuing) (in GBP per share)	(0.048)	(0.001)		(0.024)
Total basic earnings per share (in GBP per share)	£ (0.056)	£ 0.002		£ (0.189)
Diluted EPS
Diluted earnings from continuing operations	£ (28)	£ 10		£ (571)
Diluted earnings from discontinued operations	(173)	(3)		(82)
Diluted total earnings	£ (201)	£ 7		£ (653)
Diluted EPS (continuing) (in GBP per share)	£ (0.008)	£ 0.003		£ (0.164)
Diluted EPS (discontinuing) (in GBP per share)	(0.048)	(0.001)		(0.024)
Diluted EPS (in GBP per share)	£ (0.056)	£ 0.002		£ (0.188)
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Dividends (Details)

Dividends (Details) - GBP (£) £ / shares in Units, £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Summary Of Dividends [Line Items]
Cash dividends paid (GBP per share)	£ 0.4937	£ 0.4900	£ 0.4783
Dividends paid	£ 922	£ 1,413	£ 892
Scrip dividend	£ 844	£ 303	£ 758
Interim dividend in respect of the current year
Summary Of Dividends [Line Items]
Cash dividends paid (GBP per share)	£ 0.1721	£ 0.1700	£ 0.1657
Dividends paid	£ 339	£ 348	£ 335
Scrip dividend	£ 282	£ 249	£ 241
Final dividend in respect of the prior year
Summary Of Dividends [Line Items]
Cash dividends paid (GBP per share)	£ 0.3216	£ 0.3200	£ 0.3126
Dividends paid	£ 583	£ 1,065	£ 557
Scrip dividend	£ 562	£ 54	£ 517

Dividends - Narrative (Details)

Dividends - Narrative (Details) £ / shares in Units, £ in Millions	12 Months Ended
	Mar. 31, 2022GBP (£)£ / shares
Summary Of Dividends [Line Items]
Dividends declared before financial statements authorised for issue (GBP per share) | £ / shares	£ 0.3376
Dividends declared before financial statements authorised for issue | £	£ 1,231

Assets held for sale and disc_3

Assets held for sale and discontinued operations - Assets and Liabilities Classified as Held-For-Sale (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	£ 10,000	£ 3,557
Total liabilities held for sale	(7,188)	£ (1,568)
Assets and liabilities classified as held for sale
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	10,000
Total liabilities held for sale	(7,188)
Net assets held for sale	2,812
The Narragansett Electric Company | Assets and liabilities classified as held for sale
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	4,129
Total liabilities held for sale	(1,658)
Net assets held for sale	2,471
The Narragansett Electric Company | Assets and liabilities classified as held for sale | Borrowings
Summary income statement and comprehensive income, discontinued operations [line items]
Total liabilities held for sale	(1,177)
The Narragansett Electric Company | Assets and liabilities classified as held for sale | Pension liabilities
Summary income statement and comprehensive income, discontinued operations [line items]
Total liabilities held for sale	(12)
The Narragansett Electric Company | Assets and liabilities classified as held for sale | Other liabilities
Summary income statement and comprehensive income, discontinued operations [line items]
Total liabilities held for sale	(469)
The Narragansett Electric Company | Assets and liabilities classified as held for sale | Goodwill
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	590
The Narragansett Electric Company | Assets and liabilities classified as held for sale | Intangible assets
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	4
The Narragansett Electric Company | Assets and liabilities classified as held for sale | Property, plant and equipment
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	3,173
The Narragansett Electric Company | Assets and liabilities classified as held for sale | Trade and other receivables
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	251
The Narragansett Electric Company | Assets and liabilities classified as held for sale | Cash and cash equivalents
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	6
The Narragansett Electric Company | Assets and liabilities classified as held for sale | Other assets
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	105
UK Gas Transmission | Assets and liabilities classified as held for sale
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	5,871
Total liabilities held for sale	(5,530)
Net assets held for sale	341
UK Gas Transmission | Assets and liabilities classified as held for sale | Borrowings
Summary income statement and comprehensive income, discontinued operations [line items]
Total liabilities held for sale	(4,165)
UK Gas Transmission | Assets and liabilities classified as held for sale | Deferred tax liabilities
Summary income statement and comprehensive income, discontinued operations [line items]
Total liabilities held for sale	(803)
UK Gas Transmission | Assets and liabilities classified as held for sale | Other liabilities
Summary income statement and comprehensive income, discontinued operations [line items]
Total liabilities held for sale	(562)
UK Gas Transmission | Assets and liabilities classified as held for sale | Intangible assets
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	159
UK Gas Transmission | Assets and liabilities classified as held for sale | Property, plant and equipment
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	4,719
UK Gas Transmission | Assets and liabilities classified as held for sale | Trade and other receivables
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	215
UK Gas Transmission | Assets and liabilities classified as held for sale | Pension assets
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	664
UK Gas Transmission | Assets and liabilities classified as held for sale | Cash and cash equivalents
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	9
UK Gas Transmission | Assets and liabilities classified as held for sale | Financing derivatives
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	93
UK Gas Transmission | Assets and liabilities classified as held for sale | Other assets
Summary income statement and comprehensive income, discontinued operations [line items]
Total assets held for sale	£ 12

Assets held for sale and disc_4

Assets held for sale and discontinued operations - Narrative (Details) - GBP (£) £ in Millions	Mar. 27, 2022	Mar. 17, 2021	Jun. 30, 2019	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Disclosure of subsidiaries [line items]
Profit after tax				£ 2,354	£ 1,641	[1]	£ 1,265	[2]
Carrying value of investment				265	81	[3]	82	[3]
Discontinued operations
Disclosure of subsidiaries [line items]
Gain on disposal				0	0		9
Acquiring entity | Macquarie Infrastructure and Real Assets (MIRA) and British Columbia Investment Management Corporation (BCI) | Forecast
Disclosure of subsidiaries [line items]
Proportion of ownership interest in associate	60.00%
Quadgas HoldCo Limited
Disclosure of subsidiaries [line items]
Proportion of ownership interest disposed			39.00%
Carrying value of investment			£ 1,956
Quadgas HoldCo Limited | Discontinued operations
Disclosure of subsidiaries [line items]
Sales proceeds			1,965
Gain on disposal			£ 9
The Narragansett Electric Company
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary sold		100.00%
Profit after tax				£ 237	£ 104		£ 31
UK Gas Transmission | Forecast
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary sold	100.00%
Cash consideration received	£ 4,200
Portion of consideration received consisting of shareholding in acquirer	40.00%
Portion of cash consideration raised through debt financing	£ 2,000
UK Gas Transmission | Acquiring entity | Forecast
Disclosure of subsidiaries [line items]
Consideration for sale of associate before annualised escalation factor	£ 1,400
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[3]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Assets held for sale and disc_5

Assets held for sale and discontinued operations - Summary of Income Statement and Statement of Comprehensive Income (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Summary income statement and comprehensive income, discontinued operations [line items]
Revenue	£ 18,449	£ 13,665	[1]	£ 13,360	[2]
Operating profit	4,371	2,401	[1]	2,279	[3]
Finance income	50	58	[1]	54	[2]
Finance costs	(1,072)	(853)	[1]	(1,020)	[2]
Profit/(loss) before tax	3,441	1,664	[1]	1,400	[2]
Total profit after tax from discontinued operations	171	337	[4]	235	[2]
Amount of accretion on inflation linked liabilities	241	46		85
Items from discontinued operations that will never be reclassified to profit or loss:
Remeasurement gains/(losses) on pension assets and post-retirement benefit obligations	2,172	1,658	[4]	(782)	[4]
Net losses in respect of cash flow hedging of capital expenditure	(1)	(12)	[4]	(17)	[4]
Tax on items that will never be reclassified to profit or loss	(496)	(472)	[4]	232	[4]
Total items from continuing operations that will never be reclassified to profit or loss	1,687	1,220	[4]	(576)	[4]
Items from discontinued operations that may be reclassified subsequently to profit or loss:
Net (losses)/gains in respect of cash flow hedges	(57)	67	[4]	(121)	[4]
Net (losses)/gains in respect of cost of hedging	1	20	[4]	(80)	[4]
Tax on items that may be reclassified subsequently to profit or loss	15	(8)	[4]	33	[4]
Total items from continuing operations that may be reclassified subsequently to profit or loss	579	(1,187)	[4]	373	[4]
Other comprehensive income/(loss) for the year, net of tax	2,477	(183)	[4]	(165)	[4]
Total comprehensive income/(loss) for the year	4,831	1,458	[4]	1,100	[4]
Before exceptional items and remeasurements
Summary income statement and comprehensive income, discontinued operations [line items]
Revenue		13,665		13,360
Operating profit	3,813	2,427		2,804
Finance income	65	35		70
Finance costs	(1,146)	(900)		(999)
Profit/(loss) before tax	2,880	1,628		1,963
Exceptional items and remeasurements
Summary income statement and comprehensive income, discontinued operations [line items]
Operating profit	558	(26)		(525)
Finance income	(15)	23		(16)
Finance costs	74	47		(21)
Profit/(loss) before tax	561	36		(563)
Discontinued operations
Summary income statement and comprehensive income, discontinued operations [line items]
Revenue	1,362	1,114		1,180
Operating costs	(725)	(620)		(702)
Operating profit	637	494		478
Finance income	0	0		6
Finance costs	(230)	(75)		(147)
Profit/(loss) before tax	407	419		337
Tax	(236)	(82)		(111)
Profit after tax from discontinued operations	171	337		226
Gain on disposal	0	0		9
Total profit after tax from discontinued operations	171	337		235
Amount of accretion on inflation linked liabilities	158	38		76
Items from discontinued operations that will never be reclassified to profit or loss:
Remeasurement gains/(losses) on pension assets and post-retirement benefit obligations	309	(250)		58
Net losses on financial liability designated at fair value through profit and loss attributable to changes in own credit risk	(1)	(11)		(3)
Net losses in respect of cash flow hedging of capital expenditure	0	(2)		0
Tax on items that will never be reclassified to profit or loss	(94)	50		(20)
Total items from continuing operations that will never be reclassified to profit or loss	214	(213)		35
Items from discontinued operations that may be reclassified subsequently to profit or loss:
Net (losses)/gains in respect of cash flow hedges	1	3		(1)
Net (losses)/gains in respect of cost of hedging	(4)	(6)		2
Tax on items that may be reclassified subsequently to profit or loss	0	0		2
Total items from continuing operations that may be reclassified subsequently to profit or loss	(3)	(3)		3
Other comprehensive income/(loss) for the year, net of tax	211	(216)		38
Total comprehensive income/(loss) for the year	382	£ 121		£ 273
Discontinued operations | Exceptional items and remeasurements | UK
Summary income statement and comprehensive income, discontinued operations [line items]
Deferred tax charge arising as a result of UK tax rate change	£ 145
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[3]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[4]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Goodwill - Disclosure of goodwi

Goodwill - Disclosure of goodwill (Details) - Goodwill - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Goodwill, beginning balance	£ 4,588	£ 5,712
Exchange adjustments	223	(562)
Reclassification to held for sale (note 10)		(562)
Acquisition of WPD (note 37)	4,721
Goodwill, ending balance	£ 9,532	£ 4,588

Goodwill - Narrative (Details)

Goodwill - Narrative (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of reconciliation of changes in goodwill [line items]
Discount rate applied to cash flow projections		5.30%
US Regulated
Disclosure of reconciliation of changes in goodwill [line items]
Growth rate used to extrapolate cash flow projections	2.25%	2.10%
WPD
Disclosure of reconciliation of changes in goodwill [line items]
Growth rate used to extrapolate cash flow projections	2.50%
WPD | Actuarial assumption of terminal growth rate
Disclosure of reconciliation of changes in goodwill [line items]
Sensitivity analysis, actuarial assumption after reasonably possible change	2.00%
WPD | Actuarial assumption of discount rates
Disclosure of reconciliation of changes in goodwill [line items]
Sensitivity analysis, actuarial assumption after reasonably possible change	5.40%
Sensitivity analysis, reasonably possible change in actuarial assumption	0.20%
WPD Group
Disclosure of reconciliation of changes in goodwill [line items]
Discount rate applied to cash flow projections	5.20%
WPD DNOs
Disclosure of reconciliation of changes in goodwill [line items]
Discount rate applied to cash flow projections	4.90%
New York
Disclosure of reconciliation of changes in goodwill [line items]
Discount rate applied to cash flow projections	5.50%
New England
Disclosure of reconciliation of changes in goodwill [line items]
Discount rate applied to cash flow projections	5.60%
Goodwill
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	£ 9,532	£ 4,588	£ 5,712
Goodwill | Accumulated impairment
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	0	£ 0
Goodwill | Federal | Gross carrying amount
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	544
Goodwill | Massachusetts | Gross carrying amount
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	963
Goodwill | New York
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	3,151
Goodwill | New England
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	£ 1,510

Goodwill - Summary of goodwill

Goodwill - Summary of goodwill and intangible assets (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Goodwill
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	£ 9,532	£ 4,588	£ 5,712
Goodwill | National Grid Ventures Renewables
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	150
Goodwill | New England
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	1,510
Goodwill | New York
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	3,151
Goodwill | Western Power Distribution
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	4,721
Indefinite-lived intangibles
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	1,714
Indefinite-lived intangibles | West Midlands
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	518
Indefinite-lived intangibles | East Midlands
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	519
Indefinite-lived intangibles | South Wales
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	257
Indefinite-lived intangibles | South West
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	£ 420

Other intangible assets (Detail

Other intangible assets (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	£ 1,443
Intangible assets other than goodwill, ending balance	3,272	£ 1,443
Regulatory licenses
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	0
Intangible assets other than goodwill, ending balance	1,714	0
Software
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	757
Intangible assets other than goodwill, ending balance	698	757
Assets in the course of construction
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	686
Intangible assets other than goodwill, ending balance	£ 860	686
Gas Business Enablement System
Changes in intangible assets other than goodwill [abstract]
Amortised period (in years)	10 years
Intangible assets other than goodwill, beginning balance	£ 298
Intangible assets other than goodwill, ending balance	366	298
Intangible assets other than goodwill, in service amount	£ 152	82
UK General Ledger System
Changes in intangible assets other than goodwill [abstract]
Amortised period (in years)	10 years
Intangible assets other than goodwill, beginning balance	£ 0
Intangible assets other than goodwill, ending balance	103	0
Gross carrying amount
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	2,806	2,583
Exchange adjustments	80	(145)
Additions	528	421
Acquisition of WPD (note 37)	1,763
Disposals	(7)	(49)
Reclassifications	(42)	15
Reclassification to held for sale (note 10)	(469)	(19)
Intangible assets other than goodwill, ending balance	4,659	2,806
Gross carrying amount | Regulatory licenses
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	0	0
Exchange adjustments	0	0
Additions	0	0
Acquisition of WPD (note 37)	1,714
Disposals	0	0
Reclassifications	0	0
Reclassification to held for sale (note 10)	0	0
Intangible assets other than goodwill, ending balance	1,714	0
Gross carrying amount | Software
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	2,120	2,026
Exchange adjustments	69	(102)
Additions	15	7
Acquisition of WPD (note 37)	49
Disposals	(7)	(47)
Reclassifications	260	255
Reclassification to held for sale (note 10)	(431)	(19)
Intangible assets other than goodwill, ending balance	2,075	2,120
Gross carrying amount | Assets in the course of construction
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	686	557
Exchange adjustments	11	(43)
Additions	513	414
Acquisition of WPD (note 37)	0
Disposals	0	(2)
Reclassifications	(302)	(240)
Reclassification to held for sale (note 10)	(38)	0
Intangible assets other than goodwill, ending balance	870	686
Accumulated depreciation/amortisation
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	(1,363)	(1,288)
Exchange adjustments	(33)	61
Disposals	7	44
Reclassification to held for sale (note 10)	309	16
Amortisation charge for the year	(297)	(196)
Impairment	(10)
Intangible assets other than goodwill, ending balance	(1,387)	(1,363)
Accumulated depreciation/amortisation | Regulatory licenses
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	0	0
Exchange adjustments	0	0
Disposals	0	0
Reclassification to held for sale (note 10)	0	0
Amortisation charge for the year	0	0
Impairment	0
Intangible assets other than goodwill, ending balance	0	0
Accumulated depreciation/amortisation | Software
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	(1,363)	(1,288)
Exchange adjustments	(33)	61
Disposals	7	44
Reclassification to held for sale (note 10)	309	16
Amortisation charge for the year	(297)	(196)
Impairment	0
Intangible assets other than goodwill, ending balance	(1,377)	(1,363)
Accumulated depreciation/amortisation | Assets in the course of construction
Changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill, beginning balance	0	0
Exchange adjustments	0	0
Disposals	0	0
Reclassification to held for sale (note 10)	0	0
Amortisation charge for the year	0	0
Impairment	(10)
Intangible assets other than goodwill, ending balance	£ (10)	£ 0
Bottom of range | Software
Changes in intangible assets other than goodwill [abstract]
Amortised period (in years)	3 years
Top of range | Software
Changes in intangible assets other than goodwill [abstract]
Amortised period (in years)	10 years

Property, plant and equipment -

Property, plant and equipment - Disclosure of analysis of property, plant and equipment (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	£ 47,043
Property, plant and equipment, ending balance	57,532	£ 47,043
Cost
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	66,052	69,313
Exchange adjustments	1,872	(3,724)
Additions	5,920	4,510
Acquisition of WPD (note 37)	10,051
Disposals	(620)	(424)
Reclassifications	81	(63)
Reclassification to held for sale (note 10)	(10,016)	(3,560)
Property, plant and equipment, ending balance	73,340	66,052
Accumulated depreciation
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	(19,009)	(19,551)
Exchange adjustments	(394)	781
Disposals	428	387
Reclassifications	(41)	3
Reclassification to held for sale (note 10)	4,837	847
Depreciation charge for the year	(1,629)	(1,476)
Property, plant and equipment, ending balance	(15,808)	(19,009)
Land and buildings
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	2,876
Property, plant and equipment, ending balance	2,886	2,876
Land and buildings | Cost
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	3,752	3,897
Exchange adjustments	97	(213)
Additions	22	89
Acquisition of WPD (note 37)	200
Disposals	(165)	(6)
Reclassifications	62	96
Reclassification to held for sale (note 10)	(309)	(111)
Property, plant and equipment, ending balance	3,659	3,752
Land and buildings | Accumulated depreciation
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	(876)	(847)
Exchange adjustments	(20)	37
Disposals	29	0
Reclassifications	15	2
Reclassification to held for sale (note 10)	193	22
Depreciation charge for the year	(114)	(90)
Property, plant and equipment, ending balance	(773)	(876)
Plant and machinery
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	38,579
Property, plant and equipment, ending balance	48,581	38,579
Plant and machinery | Cost
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	56,061	59,609
Exchange adjustments	1,627	(3,308)
Additions	926	328
Acquisition of WPD (note 37)	9,512
Disposals	(367)	(344)
Reclassifications	4,063	3,007
Reclassification to held for sale (note 10)	(8,800)	(3,231)
Property, plant and equipment, ending balance	63,022	56,061
Plant and machinery | Accumulated depreciation
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	(17,482)	(18,042)
Exchange adjustments	(351)	698
Disposals	311	339
Reclassifications	(40)	(5)
Reclassification to held for sale (note 10)	4,421	798
Depreciation charge for the year	(1,300)	(1,270)
Property, plant and equipment, ending balance	(14,441)	(17,482)
Assets in the course of construction
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	5,221
Property, plant and equipment, ending balance	5,527	5,221
Assets in the course of construction | Cost
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	5,221	4,771
Exchange adjustments	111	(130)
Additions	4,843	4,023
Acquisition of WPD (note 37)	185
Disposals	0	(26)
Reclassifications	(4,133)	(3,243)
Reclassification to held for sale (note 10)	(640)	(174)
Property, plant and equipment, ending balance	5,587	5,221
Assets in the course of construction | Accumulated depreciation
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	0	0
Exchange adjustments	0	0
Disposals	0	0
Reclassifications	(18)	0
Reclassification to held for sale (note 10)	6	0
Depreciation charge for the year	(48)	0
Property, plant and equipment, ending balance	(60)	0
Motor vehicles and office equipment
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	367
Property, plant and equipment, ending balance	538	367
Motor vehicles and office equipment | Cost
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	1,018	1,036
Exchange adjustments	37	(73)
Additions	129	70
Acquisition of WPD (note 37)	154
Disposals	(88)	(48)
Reclassifications	89	77
Reclassification to held for sale (note 10)	(267)	(44)
Property, plant and equipment, ending balance	1,072	1,018
Motor vehicles and office equipment | Accumulated depreciation
Changes in property, plant and equipment [abstract]
Property, plant and equipment, beginning balance	(651)	(662)
Exchange adjustments	(23)	46
Disposals	88	48
Reclassifications	2	6
Reclassification to held for sale (note 10)	217	27
Depreciation charge for the year	(167)	(116)
Property, plant and equipment, ending balance	£ (534)	£ (651)

Property, plant and equipment_2

Property, plant and equipment - Disclosure of information in relation to property, plant and equipment (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Trade and other payables
Disclosure of detailed information about property, plant and equipment [line items]
Contributions to cost of property, plant and equipment	£ 137	£ 138
Non-current liabilities
Disclosure of detailed information about property, plant and equipment [line items]
Contributions to cost of property, plant and equipment	421	400
Contract liabilities – current
Disclosure of detailed information about property, plant and equipment [line items]
Contributions to cost of property, plant and equipment	130	66
Contract liabilities – non-current
Disclosure of detailed information about property, plant and equipment [line items]
Contributions to cost of property, plant and equipment	1,342	1,094
Property, plant and equipment | Cost
Disclosure of detailed information about property, plant and equipment [line items]
Capitalised interest included within cost	£ 2,114	£ 2,233

Property, plant and equipment_3

Property, plant and equipment - Disclosure of useful economic lives of property, plant and equipment (Details)	12 Months Ended
	Mar. 31, 2022
Weighted average | Freehold and leasehold buildings
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	41 years
Weighted average | Electricity transmission plant and wires
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	31 years
Weighted average | Electricity distribution plant
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	45 years
Weighted average | Electricity generation plant
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	12 years
Weighted average | Interconnector plant and other
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	32 years
Weighted average | Gas plant – mains, services and regulating equipment
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	55 years
Weighted average | Gas plant – storage
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	12 years
Weighted average | Gas plant – meters
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	24 years
Weighted average | Motor vehicles and office equipment
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	5 years
UK | Bottom of range | Electricity distribution plant
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	3 years
UK | Bottom of range | Interconnector plant and other
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	5 years
UK | Bottom of range | Gas plant – storage
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	5 years
UK | Bottom of range | Gas plant – meters
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	7 years
UK | Top of range | Freehold and leasehold buildings
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	60 years
UK | Top of range | Electricity transmission plant and wires
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	100 years
UK | Top of range | Electricity distribution plant
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	99 years
UK | Top of range | Interconnector plant and other
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	60 years
UK | Top of range | Gas plant – storage
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	40 years
UK | Top of range | Gas plant – meters
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	30 years
UK | Top of range | Motor vehicles and office equipment
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	30 years
US | Bottom of range | Electricity transmission plant and wires
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	45 years
US | Bottom of range | Electricity distribution plant
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	35 years
US | Bottom of range | Electricity generation plant
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	20 years
US | Bottom of range | Interconnector plant and other
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	5 years
US | Bottom of range | Gas plant – mains, services and regulating equipment
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	47 years
US | Bottom of range | Gas plant – storage
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	12 years
US | Bottom of range | Gas plant – meters
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	14 years
US | Top of range | Freehold and leasehold buildings
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	100 years
US | Top of range | Electricity transmission plant and wires
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	80 years
US | Top of range | Electricity distribution plant
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	85 years
US | Top of range | Electricity generation plant
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	93 years
US | Top of range | Interconnector plant and other
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	50 years
US | Top of range | Gas plant – mains, services and regulating equipment
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	80 years
US | Top of range | Gas plant – storage
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	65 years
US | Top of range | Gas plant – meters
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	40 years
US | Top of range | Motor vehicles and office equipment
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	26 years

Property, plant and equipment_4

Property, plant and equipment - Disclosure of sensitivity of gas assets (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
New York
Disclosure of operating segments [line items]
UELs limited to 2050, impact on depreciation expense	£ 140	£ 125
UELs limited to 2060, impact on depreciation expense	67	57
UELs limited to 2070, impact on depreciation expense	31	26
New England
Disclosure of operating segments [line items]
UELs limited to 2050, impact on depreciation expense	40	35
UELs limited to 2060, impact on depreciation expense	15	13
UELs limited to 2070, impact on depreciation expense	£ 1	£ 2

Property, plant and equipment_5

Property, plant and equipment - Disclosure of movements of right-of-use assets (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use assets, beginning balance	£ 630	£ 684
Exchange adjustments	21	(56)
Additions	104	130
Reclassifications		(15)
Acquisition of WPD (note 37)	9
Reclassification to held for sale (note 10)	(11)
Modifications of leases	(122)
Disposals	(3)
Depreciation charge for the year	(123)	(113)
Right-of-use assets, ending balance	505	630
Land and buildings
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use assets, beginning balance	365	364
Exchange adjustments	10	(30)
Additions	14	60
Reclassifications		0
Acquisition of WPD (note 37)	7
Reclassification to held for sale (note 10)	(7)
Modifications of leases	(122)
Disposals	(2)
Depreciation charge for the year	(40)	(29)
Right-of-use assets, ending balance	225	365
Plant and machinery
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use assets, beginning balance	81	95
Exchange adjustments	1	(4)
Additions	2	6
Reclassifications		0
Acquisition of WPD (note 37)	2
Reclassification to held for sale (note 10)	0
Modifications of leases	0
Disposals	0
Depreciation charge for the year	(16)	(16)
Right-of-use assets, ending balance	70	81
Assets in the course of construction
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use assets, beginning balance	0	0
Exchange adjustments	0	0
Additions	0	0
Reclassifications		0
Acquisition of WPD (note 37)	0
Reclassification to held for sale (note 10)	0
Modifications of leases	0
Disposals	0
Depreciation charge for the year	0	0
Right-of-use assets, ending balance	0	0
Motor vehicles and office equipment
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use assets, beginning balance	184	225
Exchange adjustments	10	(22)
Additions	88	64
Reclassifications		(15)
Acquisition of WPD (note 37)	0
Reclassification to held for sale (note 10)	(4)
Modifications of leases	0
Disposals	(1)
Depreciation charge for the year	(67)	(68)
Right-of-use assets, ending balance	£ 210	£ 184

Property, plant and equipment_6

Property, plant and equipment - Disclosure of information in relation to right-of-use assets (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Property, plant and equipment [abstract]
Interest expense on lease liabilities	£ (18)	£ (21)
Lease income	385	390
Expense relating to short-term and low-value leases	(14)	(13)
Variable lease payments included in lease income	£ 374	£ 376

Property, plant and equipment_7

Property, plant and equipment - Narrative (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Property, plant and equipment [abstract]
Expected future minimum sub lease payments receivable under non-cancellable sub leases	£ 108	£ 104
Gas distribution | Weighted average | US
Disclosure of detailed information about property, plant and equipment [line items]
Useful economic life, property, plant and equipment	58 years

Other non-current assets (Detai

Other non-current assets (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Subclassifications of assets, liabilities and equities [abstract]
Other receivables	£ 110	£ 45
Non-current tax assets	6	6
Prepayments	0	5
Accrued income	187	237
Other non-current assets	£ 303	£ 293

Financial and other investmen_3

Financial and other investments - Narrative (Details) £ in Millions	12 Months Ended
	Mar. 31, 2022GBP (£)category	Mar. 31, 2021GBP (£)	Mar. 31, 2020GBP (£)	Mar. 31, 2019GBP (£)
Disclosure of financial assets [line items]
Number of different categories of financial and other investments | category	4
Other equity reserves	£ (4,563)	£ (5,094)	£ (3,895)	£ (4,223)
Gain on disposal of equity instruments measured at FVOCI	12
Retained earnings
Disclosure of financial assets [line items]
Gain on disposal of equity instruments measured at FVOCI	82
FVOCI debt
Disclosure of financial assets [line items]
Other equity reserves	£ 103	£ 111	£ 31	£ 48

Financial and other investmen_4

Financial and other investments - Schedule of financial assets (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Non-current
FVOCI debt and other investments	£ 413	£ 416
FVOCI equity investments	0	99
FVTPL investments	417	240
Other non-current financial assets	830	755
Current
FVTPL investments	2,292	1,768
Financial assets at amortised cost	853	574
Other current financial assets	3,145	2,342	£ 1,998	£ 1,981
Other financial assets	3,975	3,097
Investments in short-term money market funds
Current
Other financial assets	1,936	1,412
Investments held by National Grid Partners
Current
Other financial assets	309	136
Investments in Sunrun
Current
Other financial assets	109	103
Collateral
Current
Other financial assets	806	540
Insurance company and non-qualified plan investments
Current
Other financial assets	534	589
Short term investments, restricted		42
Cash surrender value of life insurance policies
Current
Other financial assets	234	283
Other investments
Current
Other financial assets	47	34
Insurance company fund investments
Current
Other financial assets	4	18
Short term investments, restricted	£ 802	£ 480

Investments in joint ventures_3

Investments in joint ventures and associates - Disclosure of share of net assets, joint ventures and associates (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disclosure of joint ventures [line items]
Investments accounted for using equity method, beginning balance	£ 867	£ 995
Exchange adjustments	25	(58)
Additions	486	81
Share of post-tax results for the year	92	58
Share of other comprehensive income of associates, net of tax	1	1
Dividends received	(158)	(80)
Disposals	(50)	0
Other movements	(25)	(130)
Investments accounted for using equity method, ending balance	1,238	867
Joint ventures
Disclosure of joint ventures [line items]
Investments accounted for using equity method, beginning balance	638	654
Exchange adjustments	19	(36)
Additions	469	75
Share of post-tax results for the year	49	28
Share of other comprehensive income of associates, net of tax	0	0
Dividends received	(123)	(49)
Disposals	(50)	0
Other movements	(41)	(34)
Investments accounted for using equity method, ending balance	961	638
Associates
Disclosure of joint ventures [line items]
Investments accounted for using equity method, beginning balance	229	341
Exchange adjustments	6	(22)
Additions	17	6
Share of post-tax results for the year	43	30
Share of other comprehensive income of associates, net of tax	1	1
Dividends received	(35)	(31)
Disposals	0	0
Other movements	16	(96)
Investments accounted for using equity method, ending balance	£ 277	£ 229

Investments in joint ventures_4

Investments in joint ventures and associates - Narrative (Details) - GBP (£) £ in Millions	Mar. 15, 2022	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Disclosure of joint ventures [line items]
Capital commitments		£ 714	£ 141
Release of St William Homes LLP deferred income		18,449	13,665	[1]	£ 13,360	[2]
St William Homes LLP
Disclosure of joint ventures [line items]
Proportion of ownership interest disposed	50.00%
Cash consideration received	£ 413
Net gain on disposal of St William Homes LLP		228	0		0
St William Homes LLP | Exceptional items
Disclosure of joint ventures [line items]
Net gain on disposal of St William Homes LLP		228	0		0
Release of St William Homes LLP deferred income		£ 189	£ 0		£ 0
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Investments in joint ventures_5

Investments in joint ventures and associates - Disclosure of material interest in joint ventures and associates (Details) £ in Millions	12 Months Ended
	Mar. 31, 2022GBP (£)	Feb. 25, 2022lease	Mar. 31, 2021GBP (£)	Mar. 31, 2020GBP (£)
Joint ventures
Disclosure of joint ventures [line items]
Amounts payable	£ 247		£ 17	£ 0
Millennium Pipeline Company LLC
Disclosure of joint ventures [line items]
Proportion of ownership interest in associate	26.25%
BritNed Development Limited
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
Nemo Link Limited
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
Emerald Energy Venture LLC
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	51.00%
Bight Wind Holdings LLC
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	27.27%
Bight Wind Holdings LLC | Joint ventures
Disclosure of joint ventures [line items]
Number of leases won | lease		6
Amounts payable	£ 223

Investments in joint ventures_6

Investments in joint ventures and associates - Disclosure of detailed information about joint ventures and associates (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020		Mar. 31, 2019	[1]
Statement of financial position
Non-current assets	£ 76,897	£ 57,278
Cash and cash equivalents	204	157		£ 73	[1]	£ 252
Non-current liabilities	(46,234)	(37,988)
Current liabilities	(24,770)	(9,368)
Net assets	23,856	19,860
Income statement
Revenue	18,449	13,665	[2]	13,360	[3]
Other costs	(3,215)	(2,456)		(2,718)
Operating profit	4,371	2,401	[2]	2,279	[1]
Profit/(loss) before tax	3,441	1,664	[2]	1,400	[3]
Tax	(1,258)	(360)	[2]	(370)	[3]
Profit after tax from continuing operations	2,183	1,304	[4]	1,030	[3]
Group’s share of profit/(loss)	92	58	[2]	£ 87	[3]
Millennium Pipeline Company LLC
Statement of financial position
Non-current assets	800	795
Cash and cash equivalents	33	27
All other current assets	29	24
Non-current liabilities	(237)	(256)
Non-current financial liabilities	0	0
Current liabilities	(45)	(38)
Current financial liabilities	0	0
Net assets	580	552
Group’s ownership interest in joint venture/associate	152	145
Group adjustment: elimination of profits on sales to joint venture	0	0
Carrying amount of the Group’s investment	152	145
Income statement
Revenue	200	199
Depreciation and amortisation	(43)	(43)
Other costs	(20)	(21)
Operating profit	137	135
Net interest expense	(21)	(18)
Profit/(loss) before tax	116	117
Tax	0	0
Profit after tax from continuing operations	116	117
Group’s share of profit/(loss)	30	31
Group adjustment: tax credit/(charge)	(8)	(9)
Group’s share of post-tax results for the year	22	22
BritNed Development Limited
Statement of financial position
Non-current assets	390	409
Cash and cash equivalents	77	47
All other current assets	10	24
Non-current liabilities	(52)	(50)
Non-current financial liabilities	(29)	(31)
Current liabilities	(15)	(22)
Current financial liabilities	0	0
Net assets	381	377
Group’s ownership interest in joint venture/associate	191	189
Group adjustment: elimination of profits on sales to joint venture	0	0
Carrying amount of the Group’s investment	191	189
Income statement
Revenue	131	72
Depreciation and amortisation	(15)	(15)
Other costs	(9)	(15)
Operating profit	107	42
Net interest expense	(2)	(1)
Profit/(loss) before tax	105	41
Tax	(20)	(11)
Profit after tax from continuing operations	85	30
Group’s share of profit/(loss)	43	15
Group adjustment: tax credit/(charge)	0	0
Group’s share of post-tax results for the year	43	15
Nemo Link Limited
Statement of financial position
Non-current assets	515	536
Cash and cash equivalents	7	31
All other current assets	7	8
Non-current liabilities	(34)	(30)
Non-current financial liabilities	0	0
Current liabilities	(33)	(19)
Current financial liabilities	0	0
Net assets	462	526
Group’s ownership interest in joint venture/associate	231	263
Group adjustment: elimination of profits on sales to joint venture	0	0
Carrying amount of the Group’s investment	231	263
Income statement
Revenue	148	66
Depreciation and amortisation	(23)	(24)
Other costs	(6)	(6)
Operating profit	119	36
Net interest expense	(1)	0
Profit/(loss) before tax	118	36
Tax	(22)	(14)
Profit after tax from continuing operations	96	22
Group’s share of profit/(loss)	48	11
Group adjustment: tax credit/(charge)	0	0
Group’s share of post-tax results for the year	48	11
Emerald Energy Venture LLC
Statement of financial position
Non-current assets	1,070	559
Cash and cash equivalents	134	112
All other current assets	8	12
Non-current liabilities	(182)	(182)
Non-current financial liabilities	(310)	(104)
Current liabilities	(66)	(25)
Current financial liabilities	(23)	(2)
Net assets	631	370
Group’s ownership interest in joint venture/associate	322	189
Group adjustment: elimination of profits on sales to joint venture	(49)	(23)
Carrying amount of the Group’s investment	273	166
Income statement
Revenue	25	28
Depreciation and amortisation	(17)	(14)
Other costs	(145)	(22)
Operating profit	(137)	(8)
Net interest expense	(5)	0
Profit/(loss) before tax	(142)	(8)
Tax	0	0
Profit after tax from continuing operations	(142)	(8)
Group’s share of profit/(loss)	(72)	(4)
Group adjustment: tax credit/(charge)	19	1
Group’s share of post-tax results for the year	£ (53)	£ (3)
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[3]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[4]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Derivative financial instrume_3

Derivative financial instruments - Derivative Financial Instruments (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Disclosure of detailed information about financial instruments [line items]
Derivative assets	£ 587	£ 999
Derivative liabilities	(1,013)	(899)
Total	(426)	100
Derivative assets - current
Disclosure of detailed information about financial instruments [line items]
Derivative assets	282	457
Derivative liabilities - current
Disclosure of detailed information about financial instruments [line items]
Derivative liabilities	(144)	(145)
Total	138	312
Derivative assets - non-current
Disclosure of detailed information about financial instruments [line items]
Derivative assets	305	542
Derivative liabilities - non-current
Disclosure of detailed information about financial instruments [line items]
Derivative liabilities	(869)	(754)
Total	(564)	(212)
Financing derivatives
Disclosure of detailed information about financial instruments [line items]
Derivative assets	298	942
Derivative liabilities	(991)	(767)
Total	(693)	175
Commodity contract derivatives
Disclosure of detailed information about financial instruments [line items]
Derivative assets	289	57
Derivative liabilities	(22)	(132)
Total	£ 267	£ (75)

Derivative financial instrume_4

Derivative financial instruments - Financing Derivatives (Details) £ in Millions, number in Millions	Mar. 31, 2022GBP (£)	Mar. 31, 2021GBP (£)
Disclosure of detailed information about financial instruments [line items]
Derivative assets	£ 587	£ 999
Derivative liabilities	(1,013)	(899)
Total	(426)	100
Financing derivatives
Disclosure of detailed information about financial instruments [line items]
Derivative assets	298	942
Derivative liabilities	(991)	(767)
Total	£ (693)	£ 175
Derivative notional amount	(18,875)	(15,799)
Financing derivatives | GBP LIBOR
Disclosure of detailed information about financial instruments [line items]
Notional amount		£ 2,041
Financing derivatives | USD LIBOR
Disclosure of detailed information about financial instruments [line items]
Notional amount	£ 806	769
Financing derivatives | Less than 1 year
Disclosure of detailed information about financial instruments [line items]
Derivative assets	34	428
Derivative liabilities	(136)	(70)
Total	(102)	358
Financing derivatives | Over 12 months past due
Disclosure of detailed information about financial instruments [line items]
Derivative assets	264	514
Derivative liabilities	(855)	(697)
Total	(591)	(183)
Financing derivatives | In 1 to 2 years
Disclosure of detailed information about financial instruments [line items]
Derivative assets	6	10
Derivative liabilities	(29)	(14)
Total	(23)	(4)
Financing derivatives | In 2 to 3 years
Disclosure of detailed information about financial instruments [line items]
Derivative assets	28	24
Derivative liabilities	(39)	(12)
Total	(11)	12
Financing derivatives | In 3 to 4 years
Disclosure of detailed information about financial instruments [line items]
Derivative assets	0	62
Derivative liabilities	(26)	(80)
Total	(26)	(18)
Financing derivatives | In 4 to 5 years
Disclosure of detailed information about financial instruments [line items]
Derivative assets	12	4
Derivative liabilities	(16)	(42)
Total	(4)	(38)
Financing derivatives | More than 5 years
Disclosure of detailed information about financial instruments [line items]
Derivative assets	218	414
Derivative liabilities	(745)	(549)
Total	(527)	(135)
Interest rate swaps
Disclosure of detailed information about financial instruments [line items]
Derivative assets	89	325
Derivative liabilities	(97)	(159)
Total	£ (8)	£ 166
Derivative notional amount	(1,607)	(2,259)
Cross-currency interest rate swaps
Disclosure of detailed information about financial instruments [line items]
Derivative assets	£ 174	£ 601
Derivative liabilities	(642)	(351)
Total	£ (468)	£ 250
Derivative notional amount	(10,397)	(8,389)
Foreign exchange forward contracts
Disclosure of detailed information about financial instruments [line items]
Derivative assets	£ 35	£ 16
Derivative liabilities	(65)	(74)
Total	£ (30)	£ (58)
Derivative notional amount	(6,371)	(4,651)
Foreign exchange forward contracts | Capital expenditure
Disclosure of detailed information about financial instruments [line items]
Total	£ (21)	£ (32)
Inflation-linked swaps
Disclosure of detailed information about financial instruments [line items]
Derivative assets	0	0
Derivative liabilities	(187)	(183)
Total	£ (187)	£ (183)
Derivative notional amount	(500)	(500)
Deal contingent foreign exchange forward contracts
Disclosure of detailed information about financial instruments [line items]
Total	£ 0	£ (9)

Derivative financial instrume_5

Derivative financial instruments - Commodity Derivatives (Details) £ in Millions, number in Millions	12 Months Ended
	Mar. 31, 2022GBP (£)MMBTUGWh	Mar. 31, 2021GBP (£)MMBTUGWh
Disclosure of detailed information about financial instruments [line items]
Derivative assets	£ 587	£ 999
Derivative liabilities	(1,013)	(899)
Total	(426)	100
Commodity contract derivatives
Disclosure of detailed information about financial instruments [line items]
Derivative assets	289	57
Derivative liabilities	(22)	(132)
Total	267	(75)
Commodity contract derivatives | Less than 1 year
Disclosure of detailed information about financial instruments [line items]
Derivative assets	248	29
Derivative liabilities	(8)	(75)
Total	240	(46)
Commodity contract derivatives | Over 12 months past due
Disclosure of detailed information about financial instruments [line items]
Derivative assets	41	28
Derivative liabilities	(14)	(57)
Total	27	(29)
Commodity contract derivatives | In 1 to 2 years
Disclosure of detailed information about financial instruments [line items]
Derivative assets	34	7
Derivative liabilities	(6)	(24)
Total	28	(17)
Commodity contract derivatives | In 2 to 3 years
Disclosure of detailed information about financial instruments [line items]
Derivative assets	5	7
Derivative liabilities	(5)	(16)
Total	0	(9)
Commodity contract derivatives | In 3 to 4 years
Disclosure of detailed information about financial instruments [line items]
Derivative assets	2	7
Derivative liabilities	(2)	(7)
Total	0	0
Commodity contract derivatives | In 4 to 5 years
Disclosure of detailed information about financial instruments [line items]
Derivative assets	0	6
Derivative liabilities	(1)	(5)
Total	(1)	1
Commodity contract derivatives | More than 5 years
Disclosure of detailed information about financial instruments [line items]
Derivative assets	0	1
Derivative liabilities	0	(5)
Total	0	(4)
Forward purchases of gas
Disclosure of detailed information about financial instruments [line items]
Derivative assets	11	44
Derivative liabilities	(6)	(94)
Total	£ 5	£ (50)
Derivative non-monetary notional amount | MMBTU	28	36
Derivative term	1 year	5 years
Derivative contractual amount	86	104
Electricity capacity
Disclosure of detailed information about financial instruments [line items]
Derivative assets	£ 1	£ 2
Derivative liabilities	0	0
Total	1	2
Electricity swaps
Disclosure of detailed information about financial instruments [line items]
Derivative assets	208	10
Derivative liabilities	(10)	(33)
Total	£ 198	£ (23)
Derivative non-monetary notional amount | GWh	13,458	12,321
Electricity options
Disclosure of detailed information about financial instruments [line items]
Derivative assets	£ 5	£ 0
Derivative liabilities	0	(1)
Total	5	(1)
Gas swaps
Disclosure of detailed information about financial instruments [line items]
Derivative assets	29	1
Derivative liabilities	(6)	(3)
Total	£ 23	£ (2)
Derivative non-monetary notional amount | MMBTU	39	47
Gas options
Disclosure of detailed information about financial instruments [line items]
Derivative assets	£ 35	£ 0
Derivative liabilities	0	(1)
Total	£ 35	£ (1)
Derivative non-monetary notional amount | MMBTU	59	40

Inventories and current intan_3

Inventories and current intangible assets (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Subclassifications of assets, liabilities and equities [abstract]
Fuel stocks	£ 96	£ 94
Raw materials and consumables	297	253
Current intangible assets – emission allowances	118	92
Inventories and current intangible assets	511	439
Inventory valuation reserve	£ 7	£ 10

Trade and other receivables - S

Trade and other receivables - Summary of Trade and Other Receivables (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Trade and other receivables [abstract]
Trade receivables	£ 2,661	£ 2,152
Accrued income	1,110	886
Provision for impairment of receivables and accrued income	(741)	(672)
Trade receivables and accrued income, net	3,030	2,366
Prepayments	429	387
Contract assets	33	13
Other receivables	223	153
Trade and other receivables	£ 3,715	£ 2,919

Trade and other receivables - P

Trade and other receivables - Provision for Impairment of Receivables (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]
Allowance account for credit losses of financial assets, beginning balance	£ 672
Allowance account for credit losses of financial assets, ending balance	741	£ 672
Trade receivables
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]
Allowance account for credit losses of financial assets, beginning balance	672	512
Exchange adjustments	31	(57)
Charge for the year, net of recoveries	167	326
Uncollectible amounts written off	(124)	(59)
Reclassification to held for sale (note 10)	(5)	(50)
Allowance account for credit losses of financial assets, ending balance	£ 741	£ 672

Trade and other receivables - T

Trade and other receivables - Trade Receivables, Accrued Income and Provision Split by Geography (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Disclosure of financial assets [line items]
Trade receivables	£ 3,709	£ 3,522
Accrued income	1,110	886
Trade receivables and accrued income, net	3,030	2,366
UK
Disclosure of financial assets [line items]
Trade receivables and accrued income, net	1,024	751
US
Disclosure of financial assets [line items]
Trade receivables and accrued income, net	2,006	1,615
Gross carrying amount
Disclosure of financial assets [line items]
Accrued income	1,110	886
Gross carrying amount | UK
Disclosure of financial assets [line items]
Accrued income	715	547
Gross carrying amount | US
Disclosure of financial assets [line items]
Accrued income	395	339
Trade receivables | Gross carrying amount
Disclosure of financial assets [line items]
Trade receivables	2,661	2,152
Trade receivables | Gross carrying amount | UK
Disclosure of financial assets [line items]
Trade receivables	352	227
Trade receivables | Gross carrying amount | US
Disclosure of financial assets [line items]
Trade receivables	2,309	1,925
Trade receivables | Accumulated impairment
Disclosure of financial assets [line items]
Trade receivables	(741)	(672)
Trade receivables | Accumulated impairment | UK
Disclosure of financial assets [line items]
Trade receivables	(43)	(23)
Trade receivables | Accumulated impairment | US
Disclosure of financial assets [line items]
Trade receivables	£ (698)	£ (649)

Trade and other receivables - N

Trade and other receivables - Narrative (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020	[2]
Disclosure of financial assets [line items]
Trade receivables	£ 3,709	£ 3,522
Impairment loss recognised in profit or loss, trade receivables	167	325	[1]	£ 234
Before exceptional items and remeasurements
Disclosure of financial assets [line items]
Provision for bad and doubtful debts	139
Impairment loss recognised in profit or loss, trade receivables		325
Trade receivables
Disclosure of financial assets [line items]
Provision for bad and doubtful debts	167	326
Retail customer receivables
Disclosure of financial assets [line items]
Trade receivables	£ 2,243	£ 1,852
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Trade and other receivables - A

Trade and other receivables - Average Expected Loss Rates and Gross Balances for the Retail Customer Receivables in our US Operations (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Disclosure of financial assets [line items]
Trade receivables	£ 3,709	£ 3,522
Accrued income
Disclosure of financial assets [line items]
Expected credit loss rate	5.00%	7.00%
Trade receivables	£ 382	£ 322
Retail customer receivables
Disclosure of financial assets [line items]
Trade receivables	£ 2,243	£ 1,852
0 – 30 days past due | Retail customer receivables
Disclosure of financial assets [line items]
Expected credit loss rate	5.00%	7.00%
Trade receivables	£ 731	£ 580
30 – 60 days past due | Retail customer receivables
Disclosure of financial assets [line items]
Expected credit loss rate	20.00%	24.00%
Trade receivables	£ 213	£ 155
60 – 90 days past due | Retail customer receivables
Disclosure of financial assets [line items]
Expected credit loss rate	32.00%	36.00%
Trade receivables	£ 123	£ 108
3 – 6 months past due | Retail customer receivables
Disclosure of financial assets [line items]
Expected credit loss rate	41.00%	52.00%
Trade receivables	£ 161	£ 140
6 – 12 months past due | Retail customer receivables
Disclosure of financial assets [line items]
Expected credit loss rate	56.00%	66.00%
Trade receivables	£ 177	£ 180
Over 12 months past due | Retail customer receivables
Disclosure of financial assets [line items]
Expected credit loss rate	71.00%	71.00%
Trade receivables	£ 456	£ 367

Cash and cash equivalents (Deta

Cash and cash equivalents (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	[1]	Mar. 31, 2019	[1]
Cash and cash equivalents [abstract]
Restricted cash and cash equivalents	£ 14	£ 12
Cash at bank	204	117
Short-term deposits	0	40
Cash and cash equivalents	£ 204	£ 157	£ 73		£ 252
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Borrowings - Current and Non-Cu

Borrowings - Current and Non-Current Borrowings (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Nov. 04, 2021	Mar. 31, 2021	Mar. 31, 2020
Current
Bank loans	£ 8,976		£ 1,022
Bonds	1,735		1,987
Commercial paper	1,303		628
Lease liabilities	107		99
Other loans	0		1
Current portion of non-current borrowings	12,121		3,737
Non-current
Bank loans	2,211		2,532
Bonds	30,682		24,209
Lease liabilities	451		586
Other loans	0		156
Non-current portion of non-current borrowings	33,344		27,483
Total borrowings	45,465		31,220	£ 30,794
Liability held at fair value through profit and loss	0	£ 699	£ 682
Western Power Distribution
Current
Bank loans	£ 8,179

Borrowings - Borrowings Repayme

Borrowings - Borrowings Repayment Schedule (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of detailed information about borrowings [line items]
Borrowings	£ 45,465	£ 31,220	£ 30,794
Less than 1 year
Disclosure of detailed information about borrowings [line items]
Borrowings	12,121	3,737
In 1 to 2 years
Disclosure of detailed information about borrowings [line items]
Borrowings	1,410	1,745
In 2 to 3 years
Disclosure of detailed information about borrowings [line items]
Borrowings	2,544	889
In 3 to 4 years
Disclosure of detailed information about borrowings [line items]
Borrowings	2,580	2,206
In 4 to 5 years
Disclosure of detailed information about borrowings [line items]
Borrowings	2,493	1,833
More than 5 years | By instalments
Disclosure of detailed information about borrowings [line items]
Borrowings	869	927
More than 5 years | Other than by instalments
Disclosure of detailed information about borrowings [line items]
Borrowings	£ 23,448	£ 19,883

Borrowings - Narrative (Details

Borrowings - Narrative (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Nov. 30, 2021	Nov. 04, 2021	Mar. 31, 2020
Disclosure of fair value measurement of liabilities [line items]
Borrowings	£ 45,465	£ 31,220			£ 30,794
Collateral received	60	582
Lease liabilities	558	685
Liability held at fair value through profit and loss	0	682		£ 699
Change in fair value	0	1
Difference between carrying amount of financial liability and amount contractually required to pay at maturity to holder of obligation	0	2
Financial liabilities at fair value through profit or loss
Disclosure of fair value measurement of liabilities [line items]
Borrowings		684	£ 699
GBP LIBOR
Disclosure of fair value measurement of liabilities [line items]
Borrowings	314	328
USD LIBOR
Disclosure of fair value measurement of liabilities [line items]
Borrowings	110	59
Lease liabilities	181	173
Borrowings
Disclosure of fair value measurement of liabilities [line items]
Notional amount	44,055	31,010
At fair value
Disclosure of fair value measurement of liabilities [line items]
Borrowings	45,624	34,676
At fair value | Level 1
Disclosure of fair value measurement of liabilities [line items]
Borrowings	24,454	20,333
At fair value | Level 2
Disclosure of fair value measurement of liabilities [line items]
Borrowings	£ 21,170	£ 14,343

Borrowings - Lease Obligations

Borrowings - Lease Obligations (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Gross lease liabilities	£ 673	£ 899
Less: finance charges allocated to future periods	(115)	(214)
Lease liabilities	558	685
Less than 1 year
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Gross lease liabilities	132	114
Lease liabilities	107	99
1 to 5 years
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Gross lease liabilities	282	321
Lease liabilities	247	267
More than 5 years
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Gross lease liabilities	259	464
Lease liabilities	£ 204	£ 319

Trade and other payables (Detai

Trade and other payables (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Subclassifications of assets, liabilities and equities [abstract]
Trade payables	£ 3,113	£ 2,165
Deferred payables	487	154
Customer contributions	137	138
Social security and other taxes	278	140
Contingent consideration	34	39
Other payables	866	881
Trade and other payables	£ 4,915	£ 3,517

Contract liabilities - Summary

Contract liabilities - Summary of Contract Liabilities (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Contract liabilities [abstract]
Current	£ 130	£ 66
Non-current	1,342	1,094
Total contract liabilities	£ 1,472	£ 1,160	£ 1,158

Contract liabilities - Signific

Contract liabilities - Significant Changes in Contract Liabilities (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Increase (Decrease) in Contract Liabilities [Roll Forward]
As at 1 April	£ 1,160	£ 1,158
Exchange adjustments	29	(65)
Revenue recognised that was included in the contract liability balance at the beginning of the period	(53)	(96)
Increases due to cash received, excluding amounts recognised as revenue during the period	510	262
Reclassification to held for sale (note 10)	(174)	(99)
At 31 March	£ 1,472	£ 1,160

Other non-current liabilities_2

Other non-current liabilities (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Subclassifications of assets, liabilities and equities [abstract]
Deferred income	£ 41	£ 78
Customer contributions	421	400
Contingent consideration	7	18
Other payables	336	347
Other non-current liabilities	£ 805	£ 843

Pensions and other post-retir_3

Pensions and other post-retirement benefits - Narrative (Details) £ in Millions	12 Months Ended
	Mar. 31, 2022GBP (£)plan	Mar. 31, 2021GBP (£)	Mar. 31, 2020GBP (£)
Disclosure of defined benefit plans [line items]
Employer contributions	£ 300	£ 274
Plan assets
Disclosure of defined benefit plans [line items]
Employer contributions	£ 300	274
US | Bottom of range
Disclosure of defined benefit plans [line items]
Defined contribution plan, employer matching contribution percent of gross pay	8.00%
Defined contribution plan, employer core contribution as a percent of salary	3.00%
Defined contribution plan, employer matching contribution, percent of match	25.00%
US | Top of range
Disclosure of defined benefit plans [line items]
Defined contribution plan, employer matching contribution percent of gross pay	10.00%
Defined contribution plan, employer core contribution as a percent of salary	9.00%
Defined contribution plan, employer matching contribution, percent of match	50.00%
Pensions | UK
Disclosure of defined benefit plans [line items]
Recovery plan payments to be paid	£ 130
Employer contributions, excluding recovery plan payments	83	50	£ 70
Value of security arrangements	286
Maximum additional amounts payable	675
Employer contributions	£ 167	138
Weighted average duration of defined benefit obligation	14 years
Pensions | UK | Plan assets
Disclosure of defined benefit plans [line items]
Employer contributions	£ 167	138
Pensions | US
Disclosure of defined benefit plans [line items]
Number of defined benefit plans | plan	4
Employer contributions	£ 116	110
Weighted average duration of defined benefit obligation	13 years
Pensions | US | Plan assets
Disclosure of defined benefit plans [line items]
Employer contributions	£ 116	110
Other post-retirement benefits | US
Disclosure of defined benefit plans [line items]
Employer contributions	£ 17	26
Weighted average duration of defined benefit obligation	15 years
Other post-retirement benefits | US | Plan assets
Disclosure of defined benefit plans [line items]
Employer contributions	£ 17	£ 26
National Grid UK Retirement Plan (NGUKRP) | UK | Top of range
Disclosure of defined benefit plans [line items]
Defined contribution plan, employer matching contribution percent of gross pay	12.00%

Pensions and other post-retir_4

Pensions and other post-retirement benefits - Actuarial assumptions (Details) - year	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
UK | Pensions
Disclosure of defined benefit plans [line items]
Discount rate – past service	2.78%	2.00%	2.35%
Discount rate – future service	2.85%	2.15%	2.35%
Rate of increase in RPI – past service	3.60%	3.15%	2.65%
Rate of increase in RPI – future service	3.33%	3.00%	2.45%
Salary increases	3.47%	3.40%	2.90%
Assumed life expectations for a retiree age 65 today: Males	22	21.8	22.1
Assumed life expectations for a retiree age 65 today: Females	23.8	23.7	23.8
Assumed life expectations for a retiree age 65 today: In 20 years: Males	23.2	23.1	23.3
Assumed life expectations for a retiree age 65 today: In 20 years: Females	25.2	25.2	25.3
UK | Pensions | Active members
Disclosure of defined benefit plans [line items]
Defined benefit obligation, member concentration percentage	16.00%	8.00%
UK | Pensions | Deferred members
Disclosure of defined benefit plans [line items]
Defined benefit obligation, member concentration percentage	10.00%	14.00%
UK | Pensions | Pensioner members
Disclosure of defined benefit plans [line items]
Defined benefit obligation, member concentration percentage	74.00%	78.00%
US | Pensions
Disclosure of defined benefit plans [line items]
Discount rate – past service	3.65%	3.25%	3.30%
Discount rate – future service	3.65%	3.25%	3.30%
Salary increases	4.60%	4.30%	3.50%
Assumed life expectations for a retiree age 65 today: Males	21.4	21.6	20.9
Assumed life expectations for a retiree age 65 today: Females	23.6	24	23.4
Assumed life expectations for a retiree age 65 today: In 20 years: Males	23.1	23.2	22.5
Assumed life expectations for a retiree age 65 today: In 20 years: Females	25.3	25.5	25.1
US | Pensions | Active members
Disclosure of defined benefit plans [line items]
Defined benefit obligation, member concentration percentage	36.00%	35.00%
US | Pensions | Deferred members
Disclosure of defined benefit plans [line items]
Defined benefit obligation, member concentration percentage	9.00%	9.00%
US | Pensions | Pensioner members
Disclosure of defined benefit plans [line items]
Defined benefit obligation, member concentration percentage	55.00%	56.00%
US | Other post-retirement benefits
Disclosure of defined benefit plans [line items]
Discount rate – past service	3.65%	3.25%	3.30%
Discount rate – future service	3.65%	3.25%	3.30%
Salary increases	4.60%	4.30%	3.50%
Initial healthcare cost trend rate	6.80%	7.10%	7.00%
Ultimate healthcare cost trend rate	4.50%	4.50%	4.50%
US | Other post-retirement benefits | Active members
Disclosure of defined benefit plans [line items]
Defined benefit obligation, member concentration percentage	34.00%	34.00%
US | Other post-retirement benefits | Pensioner members
Disclosure of defined benefit plans [line items]
Defined benefit obligation, member concentration percentage	66.00%	66.00%

Pensions and other post-retir_5

Pensions and other post-retirement benefits - Amounts recognized in consolidated statement of financial position (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of defined benefit plans [line items]
Funding surplus/(deficit)	£ 3,075	£ 715
Other post-employment liabilities	(71)	(66)
Liabilities	(810)	(1,032)
Assets	3,885	1,747
Funded obligations
Disclosure of defined benefit plans [line items]
Present value of funded obligations	(23,541)	(23,283)
Fair value of plan assets	27,013	24,388
Funding surplus/(deficit)	3,472	1,105
Unfunded obligations
Disclosure of defined benefit plans [line items]
Present value of funded obligations	(326)	(324)
Pensions | UK
Disclosure of defined benefit plans [line items]
Fair value of plan assets	16,865	14,680	£ 14,364
Funding surplus/(deficit)	2,590	1,035
Other post-employment liabilities	0	0
Liabilities	(78)	(74)
Assets	2,668	1,109
Pensions | US
Disclosure of defined benefit plans [line items]
Fair value of plan assets	7,263	6,909	6,972
Funding surplus/(deficit)	484	(22)
Other post-employment liabilities	0	0
Liabilities	(248)	(393)
Assets	732	371
Pensions | Funded obligations | UK
Disclosure of defined benefit plans [line items]
Present value of funded obligations	(14,197)	(13,571)
Fair value of plan assets	16,865	14,680
Funding surplus/(deficit)	2,668	1,109
Pensions | Funded obligations | US
Disclosure of defined benefit plans [line items]
Present value of funded obligations	(6,531)	(6,681)
Fair value of plan assets	7,263	6,909
Funding surplus/(deficit)	732	228
Pensions | Unfunded obligations | UK
Disclosure of defined benefit plans [line items]
Present value of funded obligations	(78)	(74)
Pensions | Unfunded obligations | US
Disclosure of defined benefit plans [line items]
Present value of funded obligations	(248)	(250)
Other post-retirement benefits | US
Disclosure of defined benefit plans [line items]
Fair value of plan assets	2,885	2,799	£ 2,412
Funding surplus/(deficit)	1	(298)
Other post-employment liabilities	(71)	(66)
Liabilities	(484)	(565)
Assets	485	267
Other post-retirement benefits | Funded obligations | US
Disclosure of defined benefit plans [line items]
Present value of funded obligations	(2,813)	(3,031)
Fair value of plan assets	2,885	2,799
Funding surplus/(deficit)	72	(232)
Other post-retirement benefits | Unfunded obligations | US
Disclosure of defined benefit plans [line items]
Present value of funded obligations	£ 0	£ 0

Pensions and other post-retir_6

Pensions and other post-retirement benefits - Amounts recognised in the income statement and statement of other comprehensive income (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Included within operating costs
Administration costs	£ 20	£ 18	£ 16
Defined benefit plan costs:
Current service cost	223	175	178
Past service cost – augmentations	1	0	0
Past service cost/(credit) – redundancies	1	(1)	0
Special termination benefit cost – redundancies	9	5	2
Total included within payroll costs	234	179	180
Included within finance income and costs
Net interest (income)/cost	(2)	38	23
Total included in income statement	252	235	219
Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations	2,481	1,408	(724)
Exchange adjustments	7	186	(97)
Total included in the statement of other comprehensive income	2,488	1,594	(821)
Discontinued operations
Included within operating costs
Administration costs	4	3	4
Defined benefit plan costs:
Total included within payroll costs	10	10	10
Included within finance income and costs
Net interest (income)/cost	(2)	(13)	(11)
Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations	309	(250)	58
Pensions | UK
Included within operating costs
Administration costs	11	9	9
Defined benefit plan costs:
Current service cost	83	28	33
Past service cost – augmentations	1	0	0
Past service cost/(credit) – redundancies	1	(1)	0
Special termination benefit cost – redundancies	9	5	2
Total included within payroll costs	94	32	35
Included within finance income and costs
Net interest (income)/cost	(7)	(38)	(31)
Total included in income statement	98	3	13
Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations	1,577	(622)	143
Exchange adjustments	0	0	0
Total included in the statement of other comprehensive income	1,577	(622)	143
Actuarial loss arising from buy-in arrangement		100
Pensions | US
Included within operating costs
Administration costs	7	7	6
Defined benefit plan costs:
Current service cost	101	104	100
Past service cost – augmentations	0	0	0
Past service cost/(credit) – redundancies	0	0	0
Special termination benefit cost – redundancies	0	0	0
Total included within payroll costs	101	104	100
Included within finance income and costs
Net interest (income)/cost	0	35	21
Total included in income statement	108	146	127
Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations	532	1,017	(588)
Exchange adjustments	11	83	(42)
Total included in the statement of other comprehensive income	543	1,100	(630)
Other post-retirement benefits | US
Included within operating costs
Administration costs	2	2	1
Defined benefit plan costs:
Current service cost	39	43	45
Past service cost – augmentations	0	0	0
Past service cost/(credit) – redundancies	0	0	0
Special termination benefit cost – redundancies	0	0	0
Total included within payroll costs	39	43	45
Included within finance income and costs
Net interest (income)/cost	5	41	33
Total included in income statement	46	86	79
Remeasurement gains/(losses) of pension assets and post-retirement benefit obligations	372	1,013	(279)
Exchange adjustments	(4)	103	(55)
Total included in the statement of other comprehensive income	£ 368	£ 1,116	£ (334)

Pensions and other post-retir_7

Pensions and other post-retirement benefits - Reconciliation of the net defined benefit liability (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	£ 715	£ (953)
Cost recognised in the income statement (including discontinued operations)	(252)	(235)	£ (219)
Remeasurement and foreign exchange effects recognised in the statement of other comprehensive income	2,488	1,594	(821)
Employer contributions	300	274
Other movements	(22)	(14)
Acquisition of WPD	566	0
Reclassification to held for sale	(720)	49
Closing net defined benefit asset/(liability)	3,075	715	(953)
UK | Pensions
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	1,035	1,520
Cost recognised in the income statement (including discontinued operations)	(98)	(3)	(13)
Remeasurement and foreign exchange effects recognised in the statement of other comprehensive income	1,577	(622)	143
Employer contributions	167	138
Other movements	7	2
Acquisition of WPD	566	0
Reclassification to held for sale	(664)	0
Closing net defined benefit asset/(liability)	2,590	1,035	1,520
US | Pensions
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	(22)	(1,113)
Cost recognised in the income statement (including discontinued operations)	(108)	(146)	(127)
Remeasurement and foreign exchange effects recognised in the statement of other comprehensive income	543	1,100	(630)
Employer contributions	116	110
Other movements	0	0
Acquisition of WPD	0	0
Reclassification to held for sale	(45)	27
Closing net defined benefit asset/(liability)	484	(22)	(1,113)
US | Other post-retirement benefits
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	(298)	(1,360)
Cost recognised in the income statement (including discontinued operations)	(46)	(86)	(79)
Remeasurement and foreign exchange effects recognised in the statement of other comprehensive income	368	1,116	(334)
Employer contributions	17	26
Other movements	(29)	(16)
Acquisition of WPD	0	0
Reclassification to held for sale	(11)	22
Closing net defined benefit asset/(liability)	£ 1	£ (298)	£ (1,360)

Pensions and other post-retir_8

Pensions and other post-retirement benefits- Change in the present value of defined benefit obligations (including unfunded obligations) (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of operating segments [line items]
Opening net defined benefit asset/(liability)	£ 715	£ (953)
Changes in net defined benefit liability (asset) [abstract]
Current service cost	(223)	(175)	£ (178)
Interest cost	2	(38)	(23)
Past service (cost)/credit – redundancies	(1)	1	0
Special termination benefit cost – redundancies	(9)	(5)	(2)
Past service cost – augmentations	(1)	0	0
Exchange adjustments	7	186	(97)
Acquisition of WPD	566	0
Reclassification to held for sale	(720)	49
Closing net defined benefit asset/(liability)	3,075	715	(953)
UK | Pensions
Disclosure of operating segments [line items]
Opening net defined benefit asset/(liability)	1,035	1,520
Changes in net defined benefit liability (asset) [abstract]
Current service cost	(83)	(28)	(33)
Interest cost	7	38	31
Past service (cost)/credit – redundancies	(1)	1	0
Special termination benefit cost – redundancies	(9)	(5)	(2)
Past service cost – augmentations	(1)	0	0
Exchange adjustments	0	0	0
Acquisition of WPD	566	0
Reclassification to held for sale	(664)	0
Closing net defined benefit asset/(liability)	2,590	1,035	1,520
US | Pensions
Disclosure of operating segments [line items]
Opening net defined benefit asset/(liability)	(22)	(1,113)
Changes in net defined benefit liability (asset) [abstract]
Current service cost	(101)	(104)	(100)
Interest cost	0	(35)	(21)
Past service (cost)/credit – redundancies	0	0	0
Special termination benefit cost – redundancies	0	0	0
Past service cost – augmentations	0	0	0
Exchange adjustments	11	83	(42)
Acquisition of WPD	0	0
Reclassification to held for sale	(45)	27
Closing net defined benefit asset/(liability)	484	(22)	(1,113)
US | Other post-retirement benefits
Disclosure of operating segments [line items]
Opening net defined benefit asset/(liability)	(298)	(1,360)
Changes in net defined benefit liability (asset) [abstract]
Current service cost	(39)	(43)	(45)
Interest cost	(5)	(41)	(33)
Past service (cost)/credit – redundancies	0	0	0
Special termination benefit cost – redundancies	0	0	0
Past service cost – augmentations	0	0	0
Exchange adjustments	(4)	103	(55)
Acquisition of WPD	0	0
Reclassification to held for sale	(11)	22
Closing net defined benefit asset/(liability)	1	(298)	(1,360)
Present value of defined benefit obligation
Disclosure of operating segments [line items]
Opening net defined benefit asset/(liability)	(23,607)	(24,626)
Changes in net defined benefit liability (asset) [abstract]
Current service cost	(223)	(175)
Interest cost	(428)	(651)
Actuarial (losses)/gains – experience	(544)	123
Actuarial gains/(losses) – demographic assumptions	304	(1)
Actuarial gains/(losses) – financial assumptions	1,908	(1,268)
Past service (cost)/credit – redundancies	(1)	1
Special termination benefit cost – redundancies	(9)	(5)
Past service cost – augmentations	(1)	0
Medicare subsidy received	(24)	(25)
Employee contributions	(8)	(1)
Benefits paid	1,481	1,246
Exchange adjustments	(467)	1,166
Acquisition of WPD	(7,096)	0
Reclassification to held for sale	4,848	609
Closing net defined benefit asset/(liability)	(23,867)	(23,607)	(24,626)
Present value of defined benefit obligation | UK | Pensions
Disclosure of operating segments [line items]
Opening net defined benefit asset/(liability)	(13,645)	(12,844)
Changes in net defined benefit liability (asset) [abstract]
Current service cost	(83)	(28)
Interest cost	(88)	(296)
Actuarial (losses)/gains – experience	(627)	(21)
Actuarial gains/(losses) – demographic assumptions	133	(1)
Actuarial gains/(losses) – financial assumptions	1,387	(1,181)
Past service (cost)/credit – redundancies	(1)	1
Special termination benefit cost – redundancies	(9)	(5)
Past service cost – augmentations	(1)	0
Medicare subsidy received	0	0
Employee contributions	(8)	(1)
Benefits paid	919	731
Exchange adjustments	0	0
Acquisition of WPD	(7,096)	0
Reclassification to held for sale	4,844	0
Closing net defined benefit asset/(liability)	(14,275)	(13,645)	(12,844)
Present value of defined benefit obligation | US | Pensions
Disclosure of operating segments [line items]
Opening net defined benefit asset/(liability)	(6,931)	(8,085)
Changes in net defined benefit liability (asset) [abstract]
Current service cost	(101)	(104)
Interest cost	(240)	(243)
Actuarial (losses)/gains – experience	(24)	(72)
Actuarial gains/(losses) – demographic assumptions	100	0
Actuarial gains/(losses) – financial assumptions	329	(62)
Past service (cost)/credit – redundancies	0	0
Special termination benefit cost – redundancies	0	0
Past service cost – augmentations	0	0
Medicare subsidy received	0	0
Employee contributions	0	0
Benefits paid	403	371
Exchange adjustments	(327)	804
Acquisition of WPD	0	0
Reclassification to held for sale	12	460
Closing net defined benefit asset/(liability)	(6,779)	(6,931)	(8,085)
Present value of defined benefit obligation | US | Other post-retirement benefits
Disclosure of operating segments [line items]
Opening net defined benefit asset/(liability)	(3,031)	(3,697)
Changes in net defined benefit liability (asset) [abstract]
Current service cost	(39)	(43)
Interest cost	(100)	(112)
Actuarial (losses)/gains – experience	107	216
Actuarial gains/(losses) – demographic assumptions	71	0
Actuarial gains/(losses) – financial assumptions	192	(25)
Past service (cost)/credit – redundancies	0	0
Special termination benefit cost – redundancies	0	0
Past service cost – augmentations	0	0
Medicare subsidy received	(24)	(25)
Employee contributions	0	0
Benefits paid	159	144
Exchange adjustments	(140)	362
Acquisition of WPD	0	0
Reclassification to held for sale	(8)	149
Closing net defined benefit asset/(liability)	£ (2,813)	£ (3,031)	£ (3,697)

Pensions and other post-retir_9

Pensions and other post-retirement benefits - Change in fair value of plan assets (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	£ 715	£ (953)
Changes in net defined benefit liability (asset) [abstract]
Interest income	2	(38)	£ (23)
Employer contributions	300	274
Exchange adjustments	7	186	(97)
Acquisition of WPD	566	0
Reclassification to held for sale	(720)	49
Closing net defined benefit asset/(liability)	3,075	715	(953)
Actual return on plan assets	1,243	3,167
Expected contributions to plans in the following year	234	212
UK | Pensions
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	1,035	1,520
Changes in net defined benefit liability (asset) [abstract]
Interest income	7	38	31
Employer contributions	167	138
Exchange adjustments	0	0	0
Acquisition of WPD	566	0
Reclassification to held for sale	(664)	0
Closing net defined benefit asset/(liability)	2,590	1,035	1,520
Actual return on plan assets	779	915
Expected contributions to plans in the following year	146	93
Actuarial loss arising from buy-in arrangement		100
US | Pensions
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	(22)	(1,113)
Changes in net defined benefit liability (asset) [abstract]
Interest income	0	(35)	(21)
Employer contributions	116	110
Exchange adjustments	11	83	(42)
Acquisition of WPD	0	0
Reclassification to held for sale	(45)	27
Closing net defined benefit asset/(liability)	484	(22)	(1,113)
Actual return on plan assets	367	1,359
Expected contributions to plans in the following year	74	113
US | Other post-retirement benefits
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	(298)	(1,360)
Changes in net defined benefit liability (asset) [abstract]
Interest income	(5)	(41)	(33)
Employer contributions	17	26
Exchange adjustments	(4)	103	(55)
Acquisition of WPD	0	0
Reclassification to held for sale	(11)	22
Closing net defined benefit asset/(liability)	1	(298)	(1,360)
Actual return on plan assets	97	893
Expected contributions to plans in the following year	14	6
Plan assets
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	24,388	23,748
Changes in net defined benefit liability (asset) [abstract]
Interest income	430	613
Return on plan assets in excess of interest	813	2,554
Administration costs	(20)	(18)
Employer contributions	300	274
Employee contributions	8	1
Benefits paid	(1,474)	(1,244)
Exchange adjustments	474	(980)
Acquisition of WPD	7,662	0
Reclassification to held for sale	(5,568)	(560)
Closing net defined benefit asset/(liability)	27,013	24,388	23,748
Plan assets | UK | Pensions
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	14,680	14,364
Changes in net defined benefit liability (asset) [abstract]
Interest income	95	334
Return on plan assets in excess of interest	684	581
Administration costs	(11)	(9)
Employer contributions	167	138
Employee contributions	8	1
Benefits paid	(912)	(729)
Exchange adjustments	0	0
Acquisition of WPD	7,662	0
Reclassification to held for sale	(5,508)	0
Closing net defined benefit asset/(liability)	16,865	14,680	14,364
Plan assets | US | Pensions
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	6,909	6,972
Changes in net defined benefit liability (asset) [abstract]
Interest income	240	208
Return on plan assets in excess of interest	127	1,151
Administration costs	(7)	(7)
Employer contributions	116	110
Employee contributions	0	0
Benefits paid	(403)	(371)
Exchange adjustments	338	(721)
Acquisition of WPD	0	0
Reclassification to held for sale	(57)	(433)
Closing net defined benefit asset/(liability)	7,263	6,909	6,972
Plan assets | US | Other post-retirement benefits
Disclosure of net defined benefit liability (asset) [line items]
Opening net defined benefit asset/(liability)	2,799	2,412
Changes in net defined benefit liability (asset) [abstract]
Interest income	95	71
Return on plan assets in excess of interest	2	822
Administration costs	(2)	(2)
Employer contributions	17	26
Employee contributions	0	0
Benefits paid	(159)	(144)
Exchange adjustments	136	(259)
Acquisition of WPD	0	0
Reclassification to held for sale	(3)	(127)
Closing net defined benefit asset/(liability)	£ 2,885	£ 2,799	£ 2,412

Pensions and other post-reti_10

Pensions and other post-retirement benefits - Asset allocations (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
UK | Pensions
Disclosure of fair value of plan assets [line items]
Equities	£ 1,932	£ 1,356	£ 1,464
Property	1,124	669	688
Diversified alternatives	1,766	712	893
Liability-matching assets	8,113	5,864	4,982
Longevity swap	(80)	(64)	(51)
Cash and cash equivalents	477	284	251
Other (including net current assets and liabilities)	6	256	249
Fair value of plan assets	16,865	14,680	14,364
Repurchase agreements	6,600	2,500	2,800
UK | Pensions | NGUKPS Section A | Western Power Distribution
Disclosure of fair value of plan assets [line items]
Debt instruments	32	0	0
UK | Pensions | Corporate bonds
Disclosure of fair value of plan assets [line items]
Debt instruments	2,741	3,767	3,837
UK | Pensions | Government securities
Disclosure of fair value of plan assets [line items]
Debt instruments	786	1,836	2,051
UK | Pensions | Quoted
Disclosure of fair value of plan assets [line items]
Equities	1,458	555	732
Property	122	104	103
Diversified alternatives	1,334	0	0
Liability-matching assets	2,023	1,731	1,704
Longevity swap	0	0	0
Cash and cash equivalents	477	34	29
Other (including net current assets and liabilities)	16	0	0
Fair value of plan assets	8,957	7,990	8,456
UK | Pensions | Quoted | Corporate bonds
Disclosure of fair value of plan assets [line items]
Debt instruments	2,741	3,730	3,837
UK | Pensions | Quoted | Government securities
Disclosure of fair value of plan assets [line items]
Debt instruments	786	1,836	2,051
UK | Pensions | Unquoted
Disclosure of fair value of plan assets [line items]
Equities	474	801	732
Property	1,002	565	585
Diversified alternatives	432	712	893
Liability-matching assets	6,090	4,133	3,278
Longevity swap	(80)	(64)	(51)
Cash and cash equivalents	0	250	222
Other (including net current assets and liabilities)	(10)	256	249
Fair value of plan assets	7,908	6,690	5,908
UK | Pensions | Unquoted | NGUKPS
Disclosure of fair value of plan assets [line items]
Buy-in policies	2,700	4,100	3,300
UK | Pensions | Unquoted | Corporate bonds
Disclosure of fair value of plan assets [line items]
Debt instruments	0	37	0
UK | Pensions | Unquoted | Government securities
Disclosure of fair value of plan assets [line items]
Debt instruments	0	0	0
US | Pensions
Disclosure of fair value of plan assets [line items]
Equities	2,176	2,919	2,510
Property	295	264	307
Diversified alternatives	506	625	626
Infrastructure	182	130	121
Cash and cash equivalents	31	24	24
Other (including net current assets and liabilities)	15	12	(41)
Fair value of plan assets	7,263	6,909	6,972
US | Pensions | Corporate bonds
Disclosure of fair value of plan assets [line items]
Debt instruments	3,008	2,054	2,158
US | Pensions | Government securities
Disclosure of fair value of plan assets [line items]
Debt instruments	1,050	881	1,267
US | Pensions | Quoted
Disclosure of fair value of plan assets [line items]
Equities	272	560	467
Property	0	0	0
Diversified alternatives	142	167	162
Infrastructure	0	0	0
Cash and cash equivalents	31	24	24
Other (including net current assets and liabilities)	12	12	(44)
Fair value of plan assets	3,103	2,664	2,784
US | Pensions | Quoted | Corporate bonds
Disclosure of fair value of plan assets [line items]
Debt instruments	2,311	1,547	1,640
US | Pensions | Quoted | Government securities
Disclosure of fair value of plan assets [line items]
Debt instruments	335	354	535
US | Pensions | Unquoted
Disclosure of fair value of plan assets [line items]
Equities	1,904	2,359	2,043
Property	295	264	307
Diversified alternatives	364	458	464
Infrastructure	182	130	121
Cash and cash equivalents	0	0	0
Other (including net current assets and liabilities)	3	0	3
Fair value of plan assets	4,160	4,245	4,188
US | Pensions | Unquoted | Corporate bonds
Disclosure of fair value of plan assets [line items]
Debt instruments	697	507	518
US | Pensions | Unquoted | Government securities
Disclosure of fair value of plan assets [line items]
Debt instruments	715	527	732
US | Other post-retirement benefits
Disclosure of fair value of plan assets [line items]
Equities	1,198	1,722	1,390
Diversified alternatives	264	357	323
Other (including net current assets and liabilities)	185	171	132
Fair value of plan assets	2,885	2,799	2,412
US | Other post-retirement benefits | Corporate bonds
Disclosure of fair value of plan assets [line items]
Debt instruments	725	13	15
US | Other post-retirement benefits | Government securities
Disclosure of fair value of plan assets [line items]
Debt instruments	513	536	552
US | Other post-retirement benefits | Quoted
Disclosure of fair value of plan assets [line items]
Equities	185	419	353
Diversified alternatives	144	185	162
Other (including net current assets and liabilities)	0	0	0
Fair value of plan assets	1,563	1,150	1,081
US | Other post-retirement benefits | Quoted | Corporate bonds
Disclosure of fair value of plan assets [line items]
Debt instruments	723	13	15
US | Other post-retirement benefits | Quoted | Government securities
Disclosure of fair value of plan assets [line items]
Debt instruments	511	533	551
US | Other post-retirement benefits | Unquoted
Disclosure of fair value of plan assets [line items]
Equities	1,013	1,303	1,037
Diversified alternatives	120	172	161
Other (including net current assets and liabilities)	185	171	132
Fair value of plan assets	1,322	1,649	1,331
US | Other post-retirement benefits | Unquoted | Corporate bonds
Disclosure of fair value of plan assets [line items]
Debt instruments	2	0	0
US | Other post-retirement benefits | Unquoted | Government securities
Disclosure of fair value of plan assets [line items]
Debt instruments	£ 2	£ 3	£ 1

Pensions and other post-reti_11

Pensions and other post-retirement benefits - Asset allocation strategy (Details)	Mar. 31, 2022
UK | Pensions
Disclosure of fair value of plan assets [line items]
Return-seeking assets	28.00%
Liability-matching assets	72.00%
US | Pensions
Disclosure of fair value of plan assets [line items]
Return-seeking assets	41.00%
Liability-matching assets	59.00%
US | Other post-retirement benefits
Disclosure of fair value of plan assets [line items]
Return-seeking assets	51.00%
Liability-matching assets	49.00%

Provisions - Schedule of Change

Provisions - Schedule of Changes in Provisions (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Reconciliation of changes in other provisions [abstract]
Other provisions, beginning balance	£ 2,227	£ 2,654
Exchange adjustments	97	(216)
Additions	423	146
Acquisition of WPD (note 37)	66
Unused amounts reversed	(61)	(81)
Unwinding of discount	73	78
Utilised	(194)	(258)
Reclassification to held for sale (note 10)	(92)	(96)
Other provisions, ending balance	2,539	2,227
Environmental
Reconciliation of changes in other provisions [abstract]
Other provisions, beginning balance	1,700	2,071
Exchange adjustments	82	(185)
Additions	158	26
Acquisition of WPD (note 37)	0
Unused amounts reversed	(25)	(38)
Unwinding of discount	64	66
Utilised	(99)	(161)
Reclassification to held for sale (note 10)	(3)	(79)
Other provisions, ending balance	1,877	1,700
Decommissioning
Reconciliation of changes in other provisions [abstract]
Other provisions, beginning balance	244	254
Exchange adjustments	4	(9)
Additions	37	42
Acquisition of WPD (note 37)	37
Unused amounts reversed	(4)	(27)
Unwinding of discount	6	7
Utilised	(26)	(16)
Reclassification to held for sale (note 10)	(40)	(7)
Other provisions, ending balance	258	244
Restructuring
Reconciliation of changes in other provisions [abstract]
Other provisions, beginning balance	26	35
Exchange adjustments	1	(1)
Additions	16	11
Acquisition of WPD (note 37)	0
Unused amounts reversed	(1)	0
Unwinding of discount	0	0
Utilised	(22)	(19)
Reclassification to held for sale (note 10)	(3)	0
Other provisions, ending balance	17	26
Other
Reconciliation of changes in other provisions [abstract]
Other provisions, beginning balance	257	294
Exchange adjustments	10	(21)
Additions	212	67
Acquisition of WPD (note 37)	29
Unused amounts reversed	(31)	(16)
Unwinding of discount	3	5
Utilised	(47)	(62)
Reclassification to held for sale (note 10)	(46)	(10)
Other provisions, ending balance	£ 387	£ 257

Provisions - Current and Non-Cu

Provisions - Current and Non-Current Provisions (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
Current	£ 240	£ 260
Non-current	2,299	1,967
Other provisions	£ 2,539	£ 2,227	£ 2,654

Provisions - Environmental Prov

Provisions - Environmental Provision (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of other provisions [line items]
Discounted	£ 2,539	£ 2,227	£ 2,654
Environmental
Disclosure of other provisions [line items]
Discounted	1,877	1,700	£ 2,071
Real undiscounted	1,949	1,754
Real discount rate (in percent)			0.50%
Environmental | UK
Disclosure of other provisions [line items]
Discounted	152	167
Real undiscounted	£ 160	£ 171
Real discount rate (in percent)	0.50%	0.50%
Environmental | US
Disclosure of other provisions [line items]
Discounted	£ 1,725	£ 1,533
Real undiscounted	£ 1,789	£ 1,583
Real discount rate (in percent)	0.50%	0.50%

Provisions - Narrative (Details

Provisions - Narrative (Details) £ in Millions	12 Months Ended
	Mar. 31, 2022GBP (£)site	Mar. 31, 2021GBP (£)	Mar. 31, 2020GBP (£)
Disclosure of other provisions [line items]
Other provisions	£ 2,539	£ 2,227	£ 2,654
Expense of restructuring activities	423	146
Decommissioning
Disclosure of other provisions [line items]
Other provisions	258	244	254
Expense of restructuring activities	37	42
Decommissioning provision, ARO
Disclosure of other provisions [line items]
Other provisions	258	244
Restructuring
Disclosure of other provisions [line items]
Other provisions	17	26	35
Expense of restructuring activities	16	11
Other
Disclosure of other provisions [line items]
Other provisions	387	257	£ 294
Expense of restructuring activities	212	67
Liability for claims and claims adjustment
Disclosure of other provisions [line items]
Other provisions	163	166
Liability for interconnector excess revenues
Disclosure of other provisions [line items]
Other provisions	121	0
Onerous lease commitments and rates payable on surplus properties
Disclosure of other provisions [line items]
Other provisions	28	27
Emissions
Disclosure of other provisions [line items]
Other provisions	26	13
Other environment related provision
Disclosure of other provisions [line items]
Weighted average duration of cash flows			10 years
Other provisions	1,877	1,700	£ 2,071
Expense of restructuring activities	£ 158	26
Other environment related provision | US
Disclosure of other provisions [line items]
Number of Superfund sites | site	3
Weighted average duration of cash flows	11 years
Other provisions	£ 1,725	£ 1,533

Share capital - Schedule of Sha

Share capital - Schedule of Share Capital (Details) - GBP (£) £ in Millions, shares in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of classes of share capital [line items]
Equity, beginning balance	£ 19,860	£ 19,793	£ 19,568
Issued during the year in lieu of dividends	(1)	(1)	(1)
Equity, ending balance	£ 23,856	£ 19,860	£ 19,793
Share capital
Disclosure of classes of share capital [line items]
Issued capital beginning balance (in shares)	3,815	3,780
Issued during the year in lieu of dividends (in shares)	89	35
Issued capital ending balance (in shares)	3,904	3,815	3,780
Equity, beginning balance	£ 474	£ 470	£ 458
Issued during the year in lieu of dividends	11	4	12
Equity, ending balance	£ 485	£ 474	£ 470

Share capital - Narrative (Deta

Share capital - Narrative (Details) - GBP (£) £ / shares in Units, £ in Millions, shares in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020	[1]
Share Capital, Reserves And Other Equity Interest [Abstract]
Par value per share (GBP per share)	£ 0.1243129
Proceeds from issuing shares	£ 16
Amount of unclaimed dividends derecognised	£ 32
Treasury stock (in shares)	259	266
Treasury shares, market value	£ 3,038	£ 2,296
Treasury shares, gifted (in shares)	4	4
Treasury stock, reissued (in shares)	2	2
Shares reissued to employee share schemes as percent of ordinary shares	0.20%	0.20%
Treasury shares, reissued, nominal value	£ 1	£ 1
Gross proceeds from reissue of treasury shares	17	17
Purchase of own shares, employee share trusts	£ 3	£ 2	[1]	£ 6
Maximum number of treasury shares held during the year (in shares)	266	272
Treasury shares as percent of ordinary shares	6.80%	7.10%
Treasury shares, nominal value	£ 33	£ 34
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Other equity reserves (Details)

Other equity reserves (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of reserves within equity [line items]
Other equity reserves, beginning balance	£ (5,094)	£ (3,895)	£ (4,223)
Exchange adjustments	629	(1,345)	560
Net gains/(losses) taken to equity	(180)	130	(206)
Share of net (losses)/gains of associates taken to equity	1	1	(5)
Transferred to profit or loss	39	59	(31)
Net losses in respect of cash flow hedging of capital expenditure	(1)	(14)	(17)
Tax	35	(13)	42
Cash flow hedges transferred to the statement of financial position, net of tax	8	(17)	(15)
Other equity reserves, ending balance	(4,563)	(5,094)	(3,895)
Gains / (losses) on exchange adjustments related to the translation of foreign operations	754	(1,507)	545
(Losses) / gains on hedges of net investments in foreign subsidiaries	(125)	183	5
Gain on disposal of equity instruments measured at FVOCI	12
Retained earnings
Disclosure of reserves within equity [line items]
Gain on disposal of equity instruments measured at FVOCI	82
Translation
Disclosure of reserves within equity [line items]
Other equity reserves, beginning balance	(35)	1,310	750
Exchange adjustments	629	(1,345)	560
Other equity reserves, ending balance	594	(35)	1,310
Cash flow hedge
Disclosure of reserves within equity [line items]
Other equity reserves, beginning balance	(48)	(75)	61
Net gains/(losses) taken to equity	(96)	14	(142)
Share of net (losses)/gains of associates taken to equity	1	1	(5)
Transferred to profit or loss	40	56	14
Net losses in respect of cash flow hedging of capital expenditure	(1)	(14)	(17)
Tax	11	(13)	29
Cash flow hedges transferred to the statement of financial position, net of tax	8	(17)	(15)
Other equity reserves, ending balance	(85)	(48)	(75)
Cost of hedging
Disclosure of reserves within equity [line items]
Other equity reserves, beginning balance	(28)	(50)	17
Net gains/(losses) taken to equity	(2)	11	(33)
Transferred to profit or loss	(1)	3	(45)
Tax	2	8	11
Other equity reserves, ending balance	(29)	(28)	(50)
FVOCI equity
Disclosure of reserves within equity [line items]
Other equity reserves, beginning balance	51	25	34
Net gains/(losses) taken to equity	(70)	36	(13)
Tax	19	(10)	4
Other equity reserves, ending balance	0	51	25
FVOCI debt
Disclosure of reserves within equity [line items]
Other equity reserves, beginning balance	111	31	48
Net gains/(losses) taken to equity	(11)	80	(15)
Tax	3		(2)
Other equity reserves, ending balance	103	111	31
Own credit
Disclosure of reserves within equity [line items]
Other equity reserves, beginning balance	1	10	13
Net gains/(losses) taken to equity	(1)	(11)	(3)
Tax	0	2	0
Other equity reserves, ending balance	0	1	10
Capital redemption
Disclosure of reserves within equity [line items]
Other equity reserves, beginning balance	19	19	19
Other equity reserves, ending balance	19	19	19
Merger
Disclosure of reserves within equity [line items]
Other equity reserves, beginning balance	(5,165)	(5,165)	(5,165)
Other equity reserves, ending balance	£ (5,165)	£ (5,165)	£ (5,165)

Net debt - Composition of net d

Net debt - Composition of net debt (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020		Mar. 31, 2019
Subclassifications of assets, liabilities and equities [abstract]
Cash and cash equivalents (see note 20)	£ 204	£ 157	£ 73	[1]	£ 252	[1]
Current financial investments (see note 15)	3,145	2,342	1,998		1,981
Borrowings (see note 21)	(45,465)	(31,220)	(30,794)
Financing derivatives	(693)	175	133		(32)
Net debt position	£ (42,809)	£ (28,546)	£ (28,590)		£ (26,529)
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Net debt - Analysis of changes

Net debt - Analysis of changes in net debt (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020		Mar. 31, 2019
Net cash and cash equivalents
Cash and cash equivalents at start of year	£ 157	£ 73	[1]	£ 252	[1]
Cash flow	9	95		(183)
Foreign exchange movements	5	(7)	[1]	4	[1]
Reclassification to held for sale	(11)	(4)
Cash and cash equivalents at end of year	204	157		73	[1]
Financial investments
Financial investments, beginning balance	2,342	1,998		1,981
Cash flow	752	429		(42)
Fair value gains and losses	(12)	14		1
Foreign exchange movements	53	(106)		24
Interest income/(charges)	43	7		34
Other non-cash movements	(15)
Reclassification to held for sale	(87)
Financial investments, ending balance	3,145	2,342		1,998
Borrowings
Borrowings, beginning balance	(31,220)	(30,794)		(28,730)
Impact of transition to IFRS 16						£ (474)
Cash flow	(9,993)	(2,336)		450
Fair value gains and losses	286	159		(57)
Foreign exchange movements	(652)	1,710		(807)
Interest income/(charges)	(1,177)	(946)		(1,092)
Other non-cash movements	34	(136)		(84)
Reclassification to held for sale	5,543	1,123
Borrowings, ending balance	(45,465)	(31,220)		(30,794)
Financing derivatives
Financing derivatives, beginning balance	175	133		(32)
Cash flow	262	4		450
Fair value gains and losses	(604)	31		(246)
Interest income/(charges)	(59)	7		(39)
Reclassification to held for sale	(493)
Financing derivatives, ending balance	(693)	175		133
Net debt
Net debt, beginning balance	(28,546)	(28,590)		(26,529)
Impact of transition to IFRS 16						£ (474)
Cash flow	(8,970)	(1,808)		675
Fair value gains and losses	(330)	204		(302)
Foreign exchange movements	(594)	1,597		(779)
Interest income/(charges)	(1,193)	(932)		(1,097)
Other non-cash movements	19	(136)		(84)
Reclassification to held for sale	4,952	1,119
Net debt, ending balance	(42,809)	(28,546)		(28,590)
Interest received	29	7		35
Cash flows from (used in) decrease (increase) in short-term deposits and investments	781	436		(7)
Interest payable	351	£ 263		£ 246
Non-current assets
Financing derivatives
Financing derivatives, ending balance	264
Net debt
Net debt, ending balance	264
Current assets
Net cash and cash equivalents
Cash and cash equivalents at end of year	204
Financial investments
Financial investments, ending balance	3,145
Financing derivatives
Financing derivatives, ending balance	34
Net debt
Net debt, ending balance	3,383
Current liabilities
Borrowings
Borrowings, ending balance	(12,121)
Financing derivatives
Financing derivatives, ending balance	(136)
Net debt
Net debt, ending balance	(12,257)
Non-current liabilities
Borrowings
Borrowings, ending balance	(33,344)
Financing derivatives
Financing derivatives, ending balance	(855)
Net debt
Net debt, ending balance	(34,199)
Western Power Distribution
Net cash and cash equivalents
Acquisition of WPD	44
Financial investments
Acquisition of WPD	69
Borrowings
Acquisition of WPD	(8,286)
Financing derivatives
Acquisition of WPD	26
Net debt
Acquisition of WPD	£ (8,147)
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Net debt - Reconciliation of ca

Net debt - Reconciliation of cash flow from financing liabilities to cash flow statement (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Proceeds received from loans	£ 12,347	£ 5,150	[1]	£ 3,921	[1]
Repayment of loans	(1,261)	(1,654)	[1]	(3,037)	[1]
Payments of lease liabilities	(117)	(107)	[1]	(115)	[1]
Net movements in short-term borrowings	(11)	(619)	[1]	(562)	[1]
Interest paid	(1,053)	(753)	[1]	(867)	[1]
Borrowings
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Proceeds received from loans	12,347	5,150		3,921
Repayment of loans	(1,261)	(1,654)		(3,037)
Payments of lease liabilities	(117)	(107)		(115)
Net movements in short-term borrowings	(11)	(619)		(562)
Interest paid	(998)	(711)		(802)
Cash flows per financing activities section of cash flow statement	9,960	2,059		(595)
Non-net debt-related items	33	29		34
Cash flows relating to financing liabilities within net debt	9,993	2,088		(561)
Borrowings	9,993	2,088		(561)
Financing derivatives
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Cash inflows on derivatives	20	17		46
Cash outflows on derivatives	(114)	(183)		(245)
Interest paid	(55)	(42)		(65)
Cash flows per financing activities section of cash flow statement	(149)	(208)		(264)
Derivative cash (outflow)/inflow in relation to capital expenditure	(8)	10		13
Derivative cash inflows per investing section of cash flow statement	17	225		58
Derivative cash outflows per investing section of cash flow statement	(122)	(81)		(281)
Cash flows relating to financing liabilities within net debt	(262)	(54)		(474)
Financing derivatives	£ (262)	£ (54)		£ (474)
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Net debt - Reconciliation of ch

Net debt - Reconciliation of changes in liabilities arising from financing activities (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Changes in liabilities arising from financing activities [abstract]
Liabilities arising from financing activities, beginning balance	£ (31,124)	£ (30,566)	£ (28,502)
Impact of transition to IFRS 16				£ (474)
Cash flow	(9,844)	(2,178)	690
Fair value gains and losses	(186)	(142)	(288)
Foreign exchange movements	(652)	1,710	(807)
Interest charges	(1,231)	(935)	(1,101)
Other non-cash movements	34	(136)	(84)
Reclassification to held for sale	5,048	1,123
Liabilities arising from financing activities, ending balance	(46,215)	(31,124)	(30,566)
Western Power Distribution
Changes in liabilities arising from financing activities [abstract]
Acquisition of WPD	(8,260)
Borrowings
Changes in liabilities arising from financing activities [abstract]
Liabilities arising from financing activities, beginning balance	(31,220)	(30,794)	(28,730)
Impact of transition to IFRS 16				(474)
Cash flow	(9,993)	(2,336)	450
Fair value gains and losses	286	159	(57)
Foreign exchange movements	(652)	1,710	(807)
Interest charges	(1,177)	(946)	(1,092)
Other non-cash movements	34	(136)	(84)
Reclassification to held for sale	5,543	1,123
Liabilities arising from financing activities, ending balance	(45,465)	(31,220)	(30,794)
Borrowings | Western Power Distribution
Changes in liabilities arising from financing activities [abstract]
Acquisition of WPD	(8,286)
Financing derivatives
Changes in liabilities arising from financing activities [abstract]
Liabilities arising from financing activities, beginning balance	96	228	228
Impact of transition to IFRS 16				£ 0
Cash flow	149	158	240
Fair value gains and losses	(472)	(301)	(231)
Foreign exchange movements	0	0	0
Interest charges	(54)	11	(9)
Other non-cash movements	0	0	0
Reclassification to held for sale	(495)	0
Liabilities arising from financing activities, ending balance	(750)	£ 96	£ 228
Financing derivatives | Western Power Distribution
Changes in liabilities arising from financing activities [abstract]
Acquisition of WPD	£ 26

Commitments and contingencies_2

Commitments and contingencies (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Disclosure of contingent liabilities [line items]
Contracted for but not provided	£ 2,881	£ 2,716
Energy purchase commitments	18,514	15,784
Guarantees	2,564	2,836
UK Gas Transmission
Disclosure of contingent liabilities [line items]
Contracted for but not provided	205	186
Guarantee of sublease for US property (expires 2040)
Disclosure of contingent liabilities [line items]
Guarantees	149	149
Guarantees of certain obligations of Grain LNG (expire up to 2025)
Disclosure of contingent liabilities [line items]
Guarantees	31	33
Guarantees of certain obligations for construction of HVDC West Coast Link (expected expiry 2059)
Disclosure of contingent liabilities [line items]
Guarantees	84	85
Guarantees of certain obligations of National Grid North Sea Link Limited (various expiry dates)
Disclosure of contingent liabilities [line items]
Guarantees	569	584
Guarantees of certain obligations of St William Homes LLP (various expiry dates)
Disclosure of contingent liabilities [line items]
Guarantees	44	53
Guarantees of certain obligations of National Grid IFA 2 Limited (expected expiry 2022)
Disclosure of contingent liabilities [line items]
Guarantees	130	170
Guarantees of certain obligations of National Grid Viking Link Limited (expected expiry 2024)
Disclosure of contingent liabilities [line items]
Guarantees	1,177	1,276
Other guarantees and letters of credit (various expiry dates)
Disclosure of contingent liabilities [line items]
Guarantees	380	486
Less than 1 year
Disclosure of contingent liabilities [line items]
Energy purchase commitments	1,386	1,255
In 1 to 2 years
Disclosure of contingent liabilities [line items]
Energy purchase commitments	1,366	894
In 2 to 3 years
Disclosure of contingent liabilities [line items]
Energy purchase commitments	1,219	975
In 3 to 4 years
Disclosure of contingent liabilities [line items]
Energy purchase commitments	1,189	959
In 4 to 5 years
Disclosure of contingent liabilities [line items]
Energy purchase commitments	1,088	896
More than 5 years
Disclosure of contingent liabilities [line items]
Energy purchase commitments	£ 12,266	£ 10,805

Related party transactions (Det

Related party transactions (Details) £ in Millions	Mar. 15, 2022	Jun. 30, 2019	Mar. 31, 2022GBP (£)lease	Mar. 31, 2021GBP (£)	Mar. 31, 2020GBP (£)	Feb. 25, 2022lease
New York
Disclosure of transactions between related parties [line items]
Number of leases won | lease			6
Quadgas HoldCo Limited
Disclosure of transactions between related parties [line items]
Proportion of ownership interest disposed		39.00%
St William Homes LLP
Disclosure of transactions between related parties [line items]
Proportion of ownership interest disposed	50.00%
Pension plan
Disclosure of transactions between related parties [line items]
Revenue from sale of goods and services, related party transactions			£ 3	£ 3	£ 5
Joint ventures
Disclosure of transactions between related parties [line items]
Revenue from sale of goods and services, related party transactions			284	79	101
Purchases of goods and services, related party transactions			19	35	61
Amounts receivable			43	263	255
Amounts payable			247	17	0
Interest income			0	0	2
Dividends received			123	49	34
Joint ventures | Emerald Energy Venture LLC
Disclosure of transactions between related parties [line items]
Revenue from sale of goods and services, related party transactions			74	50	21
Receivables due from joint ventures			33	19	0
Joint ventures | NGET/SPT Upgrades Limited
Disclosure of transactions between related parties [line items]
Revenue from sale of goods and services, related party transactions			7	6	32
Purchases of property and other assets, related party transactions			0.3	5	58
Joint ventures | St William Homes LLP
Disclosure of transactions between related parties [line items]
Revenue from sale of goods and services, related party transactions			202	14	38
Receivables due from joint ventures				241	242
Joint ventures | BritNed Development Limited
Disclosure of transactions between related parties [line items]
Dividends received			39	18	25
Purchases of property and other assets, related party transactions			18	17	0
Joint ventures | Nemo Link Limited
Disclosure of transactions between related parties [line items]
Dividends received			77	25	8
Joint ventures | Bight Wind Holdings LLC
Disclosure of transactions between related parties [line items]
Amounts payable			223
Number of leases won | lease						6
Associates
Disclosure of transactions between related parties [line items]
Revenue from sale of goods and services, related party transactions			0	1	33
Purchases of goods and services, related party transactions			41	43	56
Amounts receivable			1	0	1
Amounts payable			4	3	4
Interest income			0	0	8
Dividends received			35	32	41
Associates | Quadgas HoldCo Limited
Disclosure of transactions between related parties [line items]
Proportion of ownership interest disposed		39.00%
Other income, sale of UK gas distribution business					31
Associates | Millennium Pipeline Company LLC
Disclosure of transactions between related parties [line items]
Purchases of goods and services, related party transactions			38	41	31
Dividends received			£ 34	£ 31	£ 32

Financial risk management - Nar

Financial risk management - Narrative Hedging (Details)	12 Months Ended
	Mar. 31, 2022
Financial Instruments [Abstract]
Hedge ratio	1

Financial risk management - Tre

Financial risk management - Treasury Credit Risk (Details) £ in Millions	Mar. 31, 2022GBP (£)
Triple ‘A’ G7 sovereign entities (AAA)
Disclosure of credit risk exposure [line items]
Maximum limit	£ 2,708
Triple ‘A’ G7 sovereign entities (AAA) | Long-term limit
Disclosure of credit risk exposure [line items]
Maximum limit	2,031
Triple ‘A’ vehicles (AAA)
Disclosure of credit risk exposure [line items]
Maximum limit	500
Triple ‘A’ vehicles (AAA) | Long-term limit
Disclosure of credit risk exposure [line items]
Maximum limit	0
Triple ‘A’ range institutions and non-G7 sovereign entities (AAA)
Disclosure of credit risk exposure [line items]
Maximum limit	2,462
Triple ‘A’ range institutions and non-G7 sovereign entities (AAA) | Long-term limit
Disclosure of credit risk exposure [line items]
Maximum limit	1,847
Double ‘A+’ G7 sovereign entities (AA+)
Disclosure of credit risk exposure [line items]
Maximum limit	2,462
Double ‘A+’ G7 sovereign entities (AA+) | Long-term limit
Disclosure of credit risk exposure [line items]
Maximum limit	1,847
Double ‘A’ range institutions (AA) | Bottom of range
Disclosure of credit risk exposure [line items]
Maximum limit	1,477
Double ‘A’ range institutions (AA) | Top of range
Disclosure of credit risk exposure [line items]
Maximum limit	1,970
Double ‘A’ range institutions (AA) | Long-term limit | Bottom of range
Disclosure of credit risk exposure [line items]
Maximum limit	1,108
Double ‘A’ range institutions (AA) | Long-term limit | Top of range
Disclosure of credit risk exposure [line items]
Maximum limit	1,477
Single ‘A’ range institutions (A) | Bottom of range
Disclosure of credit risk exposure [line items]
Maximum limit	492
Single ‘A’ range institutions (A) | Top of range
Disclosure of credit risk exposure [line items]
Maximum limit	985
Single ‘A’ range institutions (A) | Long-term limit | Bottom of range
Disclosure of credit risk exposure [line items]
Maximum limit	369
Single ‘A’ range institutions (A) | Long-term limit | Top of range
Disclosure of credit risk exposure [line items]
Maximum limit	£ 739

Financial risk management - Off

Financial risk management - Offsetting Financial Assets and Liabilities (Details) - Credit Risk - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Assets
Gross carrying amounts	£ 587	£ 999
Gross amounts offset	0	0
Net amount presented in statement of financial position	587	999
Related amounts available to be offset but not offset in statement of financial position
Financial instruments	(144)	(242)
Cash collateral received/ pledged	(105)	(561)
Net amount	338	196
Liabilities
Gross carrying amounts	(1,013)	(899)
Gross amounts offset	0	0
Net amount presented in statement of financial position	(1,013)	(899)
Related amounts available to be offset but not offset in statement of financial position
Financial instruments	144	242
Cash collateral received/ pledged	774	471
Net amount	(95)	(186)
Assets (Liabilities)
Gross carrying amounts	(426)	100
Gross amounts offset	0	0
Net amount presented in statement of financial position	(426)	100
Related amounts available to be offset but not offset in statement of financial position
Financial instruments	0	0
Cash collateral received/ pledged	669	(90)
Net amount	243	10
Financing derivatives
Liabilities
Gross carrying amounts	(991)	(767)
Gross amounts offset	0	0
Net amount presented in statement of financial position	(991)	(767)
Related amounts available to be offset but not offset in statement of financial position
Financial instruments	136	234
Cash collateral received/ pledged	771	467
Net amount	(84)	(66)
Commodity contract derivatives
Liabilities
Gross carrying amounts	(22)	(132)
Gross amounts offset	0	0
Net amount presented in statement of financial position	(22)	(132)
Related amounts available to be offset but not offset in statement of financial position
Financial instruments	8	8
Cash collateral received/ pledged	3	4
Net amount	(11)	(120)
Bank account and bank overdraft
Assets
Gross amounts offset	0	0
Financing derivatives
Assets
Gross carrying amounts	298	942
Gross amounts offset	0	0
Net amount presented in statement of financial position	298	942
Related amounts available to be offset but not offset in statement of financial position
Financial instruments	(136)	(234)
Cash collateral received/ pledged	(55)	(561)
Net amount	107	147
Commodity contract derivatives
Assets
Gross carrying amounts	289	57
Gross amounts offset	0	0
Net amount presented in statement of financial position	289	57
Related amounts available to be offset but not offset in statement of financial position
Financial instruments	(8)	(8)
Cash collateral received/ pledged	(50)	0
Net amount	£ 231	£ 49

Financial risk management - Liq

Financial risk management - Liquidity Risk (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Non-derivative financial liabilities
Lease liabilities	£ (673)	£ (899)
Less than 1 year
Non-derivative financial liabilities
Lease liabilities	(132)	(114)
Liquidity risk
Non-derivative financial liabilities
Borrowings, excluding lease liabilities	(43,498)	(31,408)
Interest payments on borrowings	(15,306)	(14,314)
Lease liabilities	(673)	(915)
Other non-interest-bearing liabilities	(4,315)	(3,557)
Contingent consideration	(45)	(64)
Derivative financial assets
Financial liabilities	(64,774)	(50,681)
Liquidity risk | Derivative contracts – receipts
Derivative financial assets
Derivative financial assets	6,719	5,710
Liquidity risk | Derivative contracts – payments
Derivative financial assets
Derivative financial assets	(6,405)	(4,850)
Liquidity risk | Commodity derivatives - receipts
Derivative financial assets
Derivative financial assets	274	27
Liquidity risk | Commodity derivatives - payments
Derivative financial assets
Derivative financial assets	(63)	(27)
Liquidity risk | Derivative contracts – receipts
Derivative financial liabilities
Derivative financial liabilities	10,958	9,299
Liquidity risk | Derivative contracts – payments
Derivative financial liabilities
Derivative financial liabilities	(12,394)	(10,462)
Liquidity risk | Commodity derivatives - receipts
Derivative financial liabilities
Derivative financial liabilities	2	12
Liquidity risk | Commodity derivatives - payments
Derivative financial liabilities
Derivative financial liabilities	(28)	(132)
Liquidity risk | Less than 1 year
Non-derivative financial liabilities
Borrowings, excluding lease liabilities	(11,589)	(3,350)
Interest payments on borrowings	(970)	(810)
Lease liabilities	(132)	(118)
Other non-interest-bearing liabilities	(3,979)	(3,207)
Contingent consideration	(37)	(40)
Derivative financial assets
Financial liabilities	(16,698)	(7,260)
Liquidity risk | Less than 1 year | Derivative contracts – receipts
Derivative financial assets
Derivative financial assets	4,512	2,162
Liquidity risk | Less than 1 year | Derivative contracts – payments
Derivative financial assets
Derivative financial assets	(4,405)	(1,700)
Liquidity risk | Less than 1 year | Commodity derivatives - receipts
Derivative financial assets
Derivative financial assets	234	21
Liquidity risk | Less than 1 year | Commodity derivatives - payments
Derivative financial assets
Derivative financial assets	(52)	(21)
Liquidity risk | Less than 1 year | Derivative contracts – receipts
Derivative financial liabilities
Derivative financial liabilities	3,149	3,773
Liquidity risk | Less than 1 year | Derivative contracts – payments
Derivative financial liabilities
Derivative financial liabilities	(3,401)	(3,899)
Liquidity risk | Less than 1 year | Commodity derivatives - receipts
Derivative financial liabilities
Derivative financial liabilities	1	12
Liquidity risk | Less than 1 year | Commodity derivatives - payments
Derivative financial liabilities
Derivative financial liabilities	(29)	(83)
Liquidity risk | In 1 to 2 years
Non-derivative financial liabilities
Borrowings, excluding lease liabilities	(1,322)	(1,690)
Interest payments on borrowings	(928)	(755)
Lease liabilities	(96)	(108)
Other non-interest-bearing liabilities	(336)	(350)
Contingent consideration	(8)	(24)
Derivative financial assets
Financial liabilities	(2,805)	(2,986)
Liquidity risk | In 1 to 2 years | Derivative contracts – receipts
Derivative financial assets
Derivative financial assets	316	926
Liquidity risk | In 1 to 2 years | Derivative contracts – payments
Derivative financial assets
Derivative financial assets	(282)	(834)
Liquidity risk | In 1 to 2 years | Commodity derivatives - receipts
Derivative financial assets
Derivative financial assets	37	4
Liquidity risk | In 1 to 2 years | Commodity derivatives - payments
Derivative financial assets
Derivative financial assets	(8)	(4)
Liquidity risk | In 1 to 2 years | Derivative contracts – receipts
Derivative financial liabilities
Derivative financial liabilities	1,008	749
Liquidity risk | In 1 to 2 years | Derivative contracts – payments
Derivative financial liabilities
Derivative financial liabilities	(1,189)	(877)
Liquidity risk | In 1 to 2 years | Commodity derivatives - receipts
Derivative financial liabilities
Derivative financial liabilities	1	0
Liquidity risk | In 1 to 2 years | Commodity derivatives - payments
Derivative financial liabilities
Derivative financial liabilities	2	(23)
Liquidity risk | In 2 to 3 years
Non-derivative financial liabilities
Borrowings, excluding lease liabilities	(2,468)	(806)
Interest payments on borrowings	(883)	(731)
Lease liabilities	(79)	(90)
Other non-interest-bearing liabilities	0	0
Contingent consideration	0	0
Derivative financial assets
Financial liabilities	(3,578)	(1,671)
Liquidity risk | In 2 to 3 years | Derivative contracts – receipts
Derivative financial assets
Derivative financial assets	1,427	833
Liquidity risk | In 2 to 3 years | Derivative contracts – payments
Derivative financial assets
Derivative financial assets	(1,313)	(780)
Liquidity risk | In 2 to 3 years | Commodity derivatives - receipts
Derivative financial assets
Derivative financial assets	3	1
Liquidity risk | In 2 to 3 years | Commodity derivatives - payments
Derivative financial assets
Derivative financial assets	(3)	(2)
Liquidity risk | In 2 to 3 years | Derivative contracts – receipts
Derivative financial liabilities
Derivative financial liabilities	2,075	451
Liquidity risk | In 2 to 3 years | Derivative contracts – payments
Derivative financial liabilities
Derivative financial liabilities	(2,336)	(533)
Liquidity risk | In 2 to 3 years | Commodity derivatives - receipts
Derivative financial liabilities
Derivative financial liabilities	0	0
Liquidity risk | In 2 to 3 years | Commodity derivatives - payments
Derivative financial liabilities
Derivative financial liabilities	(1)	(14)
Liquidity risk | More than 3 years
Non-derivative financial liabilities
Borrowings, excluding lease liabilities	(28,119)	(25,562)
Interest payments on borrowings	(12,525)	(12,018)
Lease liabilities	(366)	(599)
Other non-interest-bearing liabilities	0	0
Contingent consideration	0	0
Derivative financial assets
Financial liabilities	(41,693)	(38,764)
Liquidity risk | More than 3 years | Derivative contracts – receipts
Derivative financial assets
Derivative financial assets	464	1,789
Liquidity risk | More than 3 years | Derivative contracts – payments
Derivative financial assets
Derivative financial assets	(405)	(1,536)
Liquidity risk | More than 3 years | Commodity derivatives - receipts
Derivative financial assets
Derivative financial assets	0	1
Liquidity risk | More than 3 years | Commodity derivatives - payments
Derivative financial assets
Derivative financial assets	0	0
Liquidity risk | More than 3 years | Derivative contracts – receipts
Derivative financial liabilities
Derivative financial liabilities	4,726	4,326
Liquidity risk | More than 3 years | Derivative contracts – payments
Derivative financial liabilities
Derivative financial liabilities	(5,468)	(5,153)
Liquidity risk | More than 3 years | Commodity derivatives - receipts
Derivative financial liabilities
Derivative financial liabilities	0	0
Liquidity risk | More than 3 years | Commodity derivatives - payments
Derivative financial liabilities
Derivative financial liabilities	£ 0	£ (12)

Financial risk management - Cur

Financial risk management - Currency Risk (Details) - Currency risk - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	£ (42,809)	£ (28,546)
Cash and cash equivalents
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	204	157
Financial investments
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	3,145	2,342
Borrowings
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(45,465)	(31,220)
Pre-derivative position
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(42,116)	(28,721)
Derivative effect
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(693)	175
Trade and other receivables
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	2,195	1,669
Trade and other payables
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(4,013)	(3,085)
Other non-current liabilities
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(343)	(365)
GBP
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(22,452)	(11,758)
GBP | Cash and cash equivalents
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	111	63
GBP | Financial investments
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	1,725	1,215
GBP | Borrowings
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(22,910)	(12,210)
GBP | Pre-derivative position
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(21,074)	(10,932)
GBP | Derivative effect
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(1,378)	(826)
GBP | Trade and other receivables
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	407	282
GBP | Trade and other payables
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(1,459)	(1,207)
GBP | Other non-current liabilities
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(90)	(77)
Euro
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(203)	108
Euro | Cash and cash equivalents
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Euro | Financial investments
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Euro | Borrowings
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(7,052)	(5,351)
Euro | Pre-derivative position
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(7,052)	(5,351)
Euro | Derivative effect
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	6,849	5,459
Euro | Trade and other receivables
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Euro | Trade and other payables
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Euro | Other non-current liabilities
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	0	0
USD
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(20,175)	(16,933)
USD | Cash and cash equivalents
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	93	94
USD | Financial investments
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	1,420	1,127
USD | Borrowings
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(14,118)	(12,660)
USD | Pre-derivative position
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(12,605)	(11,439)
USD | Derivative effect
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(7,570)	(5,494)
USD | Trade and other receivables
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	1,788	1,387
USD | Trade and other payables
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(2,554)	(1,878)
USD | Other non-current liabilities
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(253)	(288)
Other
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	21	37
Other | Cash and cash equivalents
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Other | Financial investments
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Other | Borrowings
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(1,385)	(999)
Other | Pre-derivative position
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	(1,385)	(999)
Other | Derivative effect
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	1,406	1,036
Other | Trade and other receivables
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Other | Trade and other payables
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Other | Other non-current liabilities
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic	£ 0	£ 0

Financial risk management - Int

Financial risk management - Interest Rate Risk (Details) - Interest rate risk - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	£ (42,809)	£ (28,546)
Fixed rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(27,674)	(20,230)
Floating rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(10,625)	(1,897)
Inflation linked
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(4,552)	(6,478)
Other
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	42	59
Cash and cash equivalents
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	204	157
Cash and cash equivalents | Fixed rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	82	64
Cash and cash equivalents | Floating rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	118	67
Cash and cash equivalents | Inflation linked
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Cash and cash equivalents | Other
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	4	26
Financial investments
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	3,145	2,342
Financial investments | Fixed rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Financial investments | Floating rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	3,107	2,309
Financial investments | Inflation linked
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Financial investments | Other
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	38	33
Borrowings
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(45,465)	(31,220)
Borrowings | Fixed rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(30,616)	(23,163)
Borrowings | Floating rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(10,484)	(1,762)
Borrowings | Inflation linked
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(4,365)	(6,295)
Borrowings | Other
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	0	0
Pre-derivative position
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(42,116)	(28,721)
Pre-derivative position | Fixed rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(30,534)	(23,099)
Pre-derivative position | Floating rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(7,259)	614
Pre-derivative position | Inflation linked
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(4,365)	(6,295)
Pre-derivative position | Other
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	42	59
Derivative effect
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(693)	175
Derivative effect | Fixed rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	2,860	2,869
Derivative effect | Floating rate
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(3,366)	(2,511)
Derivative effect | Inflation linked
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	(187)	(183)
Derivative effect | Other
Disclosure of financial instruments by type of interest rate [line items]
Risk exposure associated with instruments sharing characteristic	£ 0	£ 0

Financial risk management - Imp

Financial risk management - Impact of Hedge Accounting in the Primary Financial Statements (Details) £ in Millions	12 Months Ended
	Mar. 31, 2022GBP (£)	Mar. 31, 2021GBP (£)	Mar. 31, 2022$ / £	Mar. 31, 2022€ / £	Mar. 31, 2022$ / €	Mar. 31, 2022	Mar. 31, 2021$ / £	Mar. 31, 2021€ / £	Mar. 31, 2021$ / €	Mar. 31, 2021	Mar. 31, 2020GBP (£)	Mar. 31, 2019GBP (£)
Disclosure of detailed information about financial instruments [line items]
Other equity reserves – cost of hedging balances	£ (4,563)	£ (5,094)									£ (3,895)	£ (4,223)
Cost of hedging
Disclosure of detailed information about financial instruments [line items]
Other equity reserves – cost of hedging balances	(29)	(28)									£ (50)	£ 17
Fair value hedges | Foreign currency and interest rate risk
Disclosure of detailed information about financial instruments [line items]
Net gains/(losses) in respect of cost of hedging	(7)	(15)
Transferred to profit or loss in respect of cost of hedging	1	1
Closing foreign exchange rate | $ / £							1.64
Fair value hedges | Foreign currency and interest rate risk | Bottom of range
Disclosure of detailed information about financial instruments [line items]
Closing foreign exchange rate				1.11	1.13			1.11	1.13
Fair value hedges | Foreign currency and interest rate risk | Bottom of range | GBP | LIBOR
Disclosure of detailed information about financial instruments [line items]
Borrowings, adjustment to interest rate basis						0.84%				0.30%
Fair value hedges | Foreign currency and interest rate risk | Bottom of range | USD | LIBOR
Disclosure of detailed information about financial instruments [line items]
Borrowings, adjustment to interest rate basis						0.68%				0.68%
Fair value hedges | Foreign currency and interest rate risk | Top of range
Disclosure of detailed information about financial instruments [line items]
Closing foreign exchange rate				1.24	1.17			1.24	1.17
Fair value hedges | Foreign currency and interest rate risk | Top of range | GBP | LIBOR
Disclosure of detailed information about financial instruments [line items]
Borrowings, adjustment to interest rate basis						3.74%				4.08%
Fair value hedges | Foreign currency and interest rate risk | Top of range | USD | LIBOR
Disclosure of detailed information about financial instruments [line items]
Borrowings, adjustment to interest rate basis						1.15%				1.15%
Fair value hedges | Foreign currency and interest rate risk | Derivative assets - current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, assets	0	0
Fair value hedges | Foreign currency and interest rate risk | Derivative assets - non-current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, assets	49	187
Fair value hedges | Foreign currency and interest rate risk | Derivative liabilities - current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, liabilities	(21)	0
Fair value hedges | Foreign currency and interest rate risk | Derivative liabilities - non-current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, liabilities	(310)	(113)
Fair value hedges | Foreign currency and interest rate risk | Cost of hedging
Disclosure of detailed information about financial instruments [line items]
Other equity reserves – cost of hedging balances	(15)	(11)
Cash flow hedges | Foreign currency and interest rate risk
Disclosure of detailed information about financial instruments [line items]
Net gains/(losses) in respect of cash flow hedges	(103)	14
Net gains/(losses) in respect of cost of hedging	16	(24)
Transferred to profit or loss in respect of cash flow hedges	43	56
Transferred to profit or loss in respect of cost of hedging	0	2
Cash flow hedges | Foreign currency and interest rate risk | Bottom of range
Disclosure of detailed information about financial instruments [line items]
Closing foreign exchange rate			1.30	1.08	1.13		1.30	1.08	1.13
Cash flow hedges | Foreign currency and interest rate risk | Bottom of range | GBP
Disclosure of detailed information about financial instruments [line items]
Borrowings, interest rate						0.976%				0.976%
Cash flow hedges | Foreign currency and interest rate risk | Bottom of range | USD
Disclosure of detailed information about financial instruments [line items]
Borrowings, interest rate						2.095%				2.513%
Cash flow hedges | Foreign currency and interest rate risk | Top of range
Disclosure of detailed information about financial instruments [line items]
Closing foreign exchange rate			1.66	1.24	1.15		1.66	1.24	1.14
Cash flow hedges | Foreign currency and interest rate risk | Top of range | GBP
Disclosure of detailed information about financial instruments [line items]
Borrowings, interest rate						7.41%				5.845%
Cash flow hedges | Foreign currency and interest rate risk | Top of range | USD
Disclosure of detailed information about financial instruments [line items]
Borrowings, interest rate						3.864%				3.864%
Cash flow hedges | Foreign currency and interest rate risk | Derivative assets - current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, assets	0	10
Cash flow hedges | Foreign currency and interest rate risk | Derivative assets - non-current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, assets	67	59
Cash flow hedges | Foreign currency and interest rate risk | Derivative liabilities - current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, liabilities	(22)	(12)
Cash flow hedges | Foreign currency and interest rate risk | Derivative liabilities - non-current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, liabilities	(303)	(255)
Cash flow hedges | Foreign currency and interest rate risk | Cost of hedging
Disclosure of detailed information about financial instruments [line items]
Other equity reserves – cost of hedging balances	(16)	(30)
Cash flow hedges | Currency risk
Disclosure of detailed information about financial instruments [line items]
Net gains/(losses) in respect of cash flow hedges	(1)	(14)
Net gains/(losses) in respect of cost of hedging	0	0
Transferred to profit or loss in respect of cash flow hedges	0	0
Transferred to profit or loss in respect of cost of hedging	0	0
Cash flow hedges | Currency risk | Bottom of range
Disclosure of detailed information about financial instruments [line items]
Closing foreign exchange rate			1.34	1.04			1.31	1.04
Cash flow hedges | Currency risk | Top of range
Disclosure of detailed information about financial instruments [line items]
Closing foreign exchange rate			1.41	1.19			1.41	1.29
Cash flow hedges | Currency risk | Derivative assets - current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, assets	1	2
Cash flow hedges | Currency risk | Derivative assets - non-current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, assets	1	1
Cash flow hedges | Currency risk | Derivative liabilities - current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, liabilities	(37)	(24)
Cash flow hedges | Currency risk | Derivative liabilities - non-current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, liabilities	(8)	(22)
Cash flow hedges | Currency risk | Cost of hedging
Disclosure of detailed information about financial instruments [line items]
Other equity reserves – cost of hedging balances	0	0
Net investment hedges
Disclosure of detailed information about financial instruments [line items]
Net gains/(losses) in respect of cost of hedging	(7)	50
Transferred to profit or loss in respect of cost of hedging	(2)	0
Closing foreign exchange rate | € / £				1.18
Net investment hedges | Bottom of range
Disclosure of detailed information about financial instruments [line items]
Closing foreign exchange rate			1.22				1.22	1.15
Net investment hedges | Top of range
Disclosure of detailed information about financial instruments [line items]
Closing foreign exchange rate			1.34				1.40	1.16
Net investment hedges | Derivative assets - current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, assets	10	5
Net investment hedges | Derivative assets - non-current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, assets	82	140
Net investment hedges | Derivative liabilities - current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, liabilities	(16)	(17)
Net investment hedges | Derivative liabilities - non-current
Disclosure of detailed information about financial instruments [line items]
Hedging instrument, liabilities	0	0
Net investment hedges | Cost of hedging
Disclosure of detailed information about financial instruments [line items]
Other equity reserves – cost of hedging balances	£ (3)	£ 6

Financial risk management - Eff

Financial risk management - Effects of Hedge Accounting on Financial Position and Performance for Each Type of Hedge (Details)	12 Months Ended
	Mar. 31, 2022GBP (£)	Mar. 31, 2021GBP (£)
Foreign currency and interest rate risk | Fair value hedges
Disclosure of detailed information about hedging instruments [line items]
Hedging instrument notional	(3,362,000,000)	(2,755,000,000)
Balance of fair value hedge adjustments in borrowings, Continuing hedges	£ 437,000,000	£ 121,000,000
Balance of fair value hedge adjustments in borrowings, Discontinued hedges	(55,000,000)	(85,000,000)
Change in value used for calculating ineffectiveness, Hedged item	340,000,000	153,000,000
Change in value used for calculating ineffectiveness, Hedging instrument	(301,000,000)	(127,000,000)
Hedge ineffectiveness	£ 39,000,000	£ 26,000,000
Foreign currency and interest rate risk | Fair value hedges | Impacted by Interest Rate Benchmark Reform amendments
Disclosure of detailed information about hedging instruments [line items]
Hedging instrument notional	(2,556,000,000)	(2,679,000,000)
Nominal amount of hedging instruments in hedging relationships to which amendments for interest rate benchmark reform are applied	£ 806,000,000
Foreign currency and interest rate risk | Fair value hedges | Borrowings
Disclosure of detailed information about hedging instruments [line items]
Hedged borrowings	2,966,000,000	£ 2,714,000,000
Foreign currency and interest rate risk | Fair value hedges | Borrowings | Current liabilities
Disclosure of detailed information about hedging instruments [line items]
Hedged borrowings	0	0
Foreign currency and interest rate risk | Fair value hedges | Borrowings | Non-current liabilities
Disclosure of detailed information about hedging instruments [line items]
Hedged borrowings	£ 2,966,000,000	£ 2,714,000,000
Foreign currency and interest rate risk | Cash flow hedges
Disclosure of detailed information about hedging instruments [line items]
Hedging instrument notional	(6,287,000,000)	(4,884,000,000)
Balance in cash flow hedge reserve, Continuing hedges	£ (48,000,000)	£ (11,000,000)
Balance in cash flow hedge reserve, Discontinued hedges	0	(6,000,000)
Change in value used for calculating ineffectiveness, Hedged item	74,000,000	(16,000,000)
Change in value used for calculating ineffectiveness, Hedging instrument	(74,000,000)	16,000,000
Hedge ineffectiveness	£ 0	£ 0
Foreign currency and interest rate risk | Cash flow hedges | Impacted by Interest Rate Benchmark Reform amendments
Disclosure of detailed information about hedging instruments [line items]
Hedging instrument notional	(100,000,000)	(176,000,000)
Currency risk | Cash flow hedges
Disclosure of detailed information about hedging instruments [line items]
Hedging instrument notional	(835,000,000)	(988,000,000)
Balance in cash flow hedge reserve, Continuing hedges	£ (40,000,000)	£ (31,000,000)
Balance in cash flow hedge reserve, Discontinued hedges	1,000,000	3,000,000
Change in value used for calculating ineffectiveness, Hedged item	18,000,000	17,000,000
Change in value used for calculating ineffectiveness, Hedging instrument	(18,000,000)	(17,000,000)
Hedge ineffectiveness	£ 0	£ 0
Currency risk | Net investment hedges
Disclosure of detailed information about hedging instruments [line items]
Hedging instrument notional	(3,489,000,000)	(2,786,000,000)
Balance in translation reserve, Continuing hedges	£ (125,000,000)	£ 183,000,000
Balance in translation reserve, Discontinued hedges	(2,643,000,000)	(2,826,000,000)
Change in value used for calculating ineffectiveness, Hedged item	125,000,000	(183,000,000)
Change in value used for calculating ineffectiveness, Hedging instrument	(125,000,000)	183,000,000
Hedge ineffectiveness	£ 0	£ 0
Currency risk | Net investment hedges | Impacted by Interest Rate Benchmark Reform amendments
Disclosure of detailed information about hedging instruments [line items]
Hedging instrument notional	0	0

Financial risk management - Fai

Financial risk management - Fair Value Analysis (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	£ 3,709	£ 3,522
Liabilities	(1,054)	(1,638)
Financial assets (liabilities)	2,655	1,884
Level 1
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	2,292	1,867
Liabilities	0	(682)
Financial assets (liabilities)	2,292	1,185
Level 2
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	949	1,370
Liabilities	(819)	(659)
Financial assets (liabilities)	130	711
Level 3
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	468	285
Liabilities	(235)	(297)
Financial assets (liabilities)	233	(12)	£ (96)
Financing derivatives
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	(991)	(767)
Financing derivatives | Level 1
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Financing derivatives | Level 2
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	(804)	(584)
Financing derivatives | Level 3
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	(187)	(183)
Commodity contract derivatives
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	(22)	(132)
Commodity contract derivatives | Level 1
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Commodity contract derivatives | Level 2
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	(15)	(75)
Commodity contract derivatives | Level 3
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	(7)	(57)
Liabilities held at fair value
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	(682)
Liabilities held at fair value | Level 1
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	(682)
Liabilities held at fair value | Level 2
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Liabilities held at fair value | Level 3
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Contingent consideration
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	(41)	(57)
Contingent consideration | Level 1
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Contingent consideration | Level 2
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Contingent consideration | Level 3
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	(41)	(57)
Investments held at FVTPL
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	2,709	2,008
Investments held at FVTPL | Level 1
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	2,292	1,768
Investments held at FVTPL | Level 2
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	0	0
Investments held at FVTPL | Level 3
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	417	240
Investments held at FVOCI
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	413	515
Investments held at FVOCI | Level 1
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	0	99
Investments held at FVOCI | Level 2
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	413	416
Investments held at FVOCI | Level 3
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	0	0
Financing derivatives
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	298	942
Financing derivatives | Level 1
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	0	0
Financing derivatives | Level 2
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	298	942
Financing derivatives | Level 3
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	0	0
Commodity contract derivatives
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	289	57
Commodity contract derivatives | Level 1
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	0	0
Commodity contract derivatives | Level 2
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	238	12
Commodity contract derivatives | Level 3
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	£ 51	£ 45

Financial risk management - Cha

Financial risk management - Changes in Level 3 Financial Instruments (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Changes In Fair Value Measurement, Assets (Liabilities) [Roll Forward]
Beginning balance	£ 1,884
Ending balance	2,655	£ 1,884
Level 3
Changes In Fair Value Measurement, Assets (Liabilities) [Roll Forward]
Beginning balance	(12)	(96)
Net gains/(losses) for the year	154	33
Purchases	110	31
Settlements	(19)	16
Reclassification to held for sale (note 10)	0	4
Ending balance	233	(12)
Level 3 | Financing derivatives
Changes In Fair Value Measurement, Assets (Liabilities) [Roll Forward]
Beginning balance	(183)	(235)
Net gains/(losses) for the year	(4)	51
Purchases	0	0
Settlements	0	1
Reclassification to held for sale (note 10)	0	0
Ending balance	(187)	(183)
(Losses)/gains on assets held at end of year	(4)	51
Level 3 | Commodity contract derivatives
Changes In Fair Value Measurement, Assets (Liabilities) [Roll Forward]
Beginning balance	(12)	2
Net gains/(losses) for the year	56	(16)
Purchases	17	(1)
Settlements	(17)	(1)
Reclassification to held for sale (note 10)	0	4
Ending balance	44	(12)
(Losses)/gains on assets held at end of year	27	(46)
Level 3 | Other
Changes In Fair Value Measurement, Assets (Liabilities) [Roll Forward]
Beginning balance	183	137
Net gains/(losses) for the year	102	(2)
Purchases	93	32
Settlements	(2)	16
Reclassification to held for sale (note 10)	0	0
Ending balance	£ 376	£ 183

Financial risk management - I_2

Financial risk management - Impacts of Reasonably Possible Changes in Significant Level 3 Assumptions (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Financing derivatives | + 20 basis points change in Limited Price Inflation (LPI) market curve
Disclosure of detailed information about financial instruments [line items]
20 basis points change in Limited Price Inflation (LPI) market curve	£ (84)	£ (83)
Financing derivatives | - 20 basis points change in LPI market curve
Disclosure of detailed information about financial instruments [line items]
–20 basis points change in LPI market curve	82	83
Commodity contract derivatives | 10% increase in commodity prices
Disclosure of detailed information about financial instruments [line items]
10% increase in commodity prices	9	3
Commodity contract derivatives | 10% decrease in commodity prices
Disclosure of detailed information about financial instruments [line items]
10% decrease in commodity prices	(8)	(1)
Commodity contract derivatives | +10% market area price change
Disclosure of detailed information about financial instruments [line items]
+10% market area price change		(4)
Commodity contract derivatives | -10% market area price change
Disclosure of detailed information about financial instruments [line items]
-10% market area price change		7
Other | +50 basis points change in discount rate
Disclosure of detailed information about financial instruments [line items]
+50 basis points change in discount rate	(10)	(5)
Other | -50 basis points change in discount rate
Disclosure of detailed information about financial instruments [line items]
-50 basis points change in discount rate	£ 10	£ 5

Financial risk management - Cap

Financial risk management - Capital Risk Management (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disclosure of credit risk exposure [line items]
Retained cash flow ratio	8.90%	6.60%
Gearing ratio	81.00%	65.00%
Interest cover ratio	4.7	4.5
Debt covenants, borrowings excluding cash and short term investments	£ 55,000
Debt covenants, borrowings excluding cash and short term investments, headroom	10,000
Non-US Subsidiaries
Disclosure of credit risk exposure [line items]
Debt covenants, total debt	35,000
US Subsidiaries
Disclosure of credit risk exposure [line items]
Debt covenants, total debt	35,000
US And Non-US subsidiaries
Disclosure of credit risk exposure [line items]
Debt covenants, total debt, headroom	£ 10,000
WPD
Disclosure of credit risk exposure [line items]
Interest coverage ratio	300.00%
Net debt to RAV gearing covenants	0.85
Net debt to RAV gearing ratio	60.00%
WPD | Minimum
Disclosure of credit risk exposure [line items]
Interest cover ratio	5
WPD | Maximum
Disclosure of credit risk exposure [line items]
Interest cover ratio	6

Borrowing facilities - Narrativ

Borrowing facilities - Narrative (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disclosure of detailed information about borrowings [line items]
Borrowings	£ 45,465	£ 31,220	£ 30,794
Bank loans	8,976	1,022
Undrawn borrowing facilities	6,914	5,525
WPD
Disclosure of detailed information about borrowings [line items]
Bank loans	8,179
In 3 to 4 years
Disclosure of detailed information about borrowings [line items]
Borrowings	2,580	2,206
Undrawn borrowing facilities	1,605	1,718
In 1 to 2 years
Disclosure of detailed information about borrowings [line items]
Renegotiated undrawn borrowing facilities	845
Borrowings	1,410	1,745
Undrawn borrowing facilities	936	1,668
Bilateral committed credit facilities
Disclosure of detailed information about borrowings [line items]
Line of credit facility, maximum borrowing capacity	5,978	5,410
Credit facilities from syndicates of banks
Disclosure of detailed information about borrowings [line items]
Line of credit facility, maximum borrowing capacity	936	115
Facilities held as backup to commercial paper and similar borrowings
Disclosure of detailed information about borrowings [line items]
Undrawn borrowing facilities	6,823	5,410
Facilities available as backup to specific US borrowings
Disclosure of detailed information about borrowings [line items]
Undrawn borrowing facilities	91	115
National Grid Gas plc | In 3 to 4 years
Disclosure of detailed information about borrowings [line items]
Undrawn borrowing facilities	350
2019 Export credit agreements
Disclosure of detailed information about borrowings [line items]
Borrowings	550	550
Export credit agency
Disclosure of detailed information about borrowings [line items]
Borrowings	1,396	1,345
Undrawn borrowing facilities	489	446
Facilities to finance the acquisition
Disclosure of detailed information about borrowings [line items]
Line of credit facility, maximum borrowing capacity	£ 8,250	£ 8,250

Borrowing facilities - Schedule

Borrowing facilities - Schedule of undrawn committed borrowing facilities (Details) - GBP (£) £ in Millions	Mar. 31, 2022	Mar. 31, 2021
Disclosure of detailed information about borrowings [line items]
Undrawn borrowing facilities	£ 6,914	£ 5,525
Less than 1 year
Disclosure of detailed information about borrowings [line items]
Undrawn borrowing facilities	0	0
In 1 to 2 years
Disclosure of detailed information about borrowings [line items]
Undrawn borrowing facilities	936	1,668
In 2 to 3 years
Disclosure of detailed information about borrowings [line items]
Undrawn borrowing facilities	4,373	534
In 3 to 4 years
Disclosure of detailed information about borrowings [line items]
Undrawn borrowing facilities	1,605	1,718
In 4 to 5 years
Disclosure of detailed information about borrowings [line items]
Undrawn borrowing facilities	0	1,605
More than 5 years
Disclosure of detailed information about borrowings [line items]
Undrawn borrowing facilities	£ 0	£ 0

Subsidiary undertakings, join_3

Subsidiary undertakings, joint ventures and associates - Subsidiaries (Details)	12 Months Ended
	Mar. 31, 2022
Sheet Road Management Company Limited
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	51.00%
Warwick Technology Park Management Company (No 2) Limited
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	60.56%
New England Hydro Finance Company, Inc.
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	53.704%
New England Hydro-Transmission Corporation
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	53.704%
New England Hydro-Transmission Electric Company Inc.
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	53.704%
Vermont Green Line Devco, LLC
Disclosure of subsidiaries [line items]
Proportion of ownership interest in subsidiary	90.00%

Subsidiary undertakings, join_4

Subsidiary undertakings, joint ventures and associates - Joint Ventures (Details)	12 Months Ended
	Mar. 31, 2022£ / sharesshares	Mar. 31, 2022€ / sharesshares
Disclosure of joint ventures [line items]
Par value per share (EUR/GBP per share) | £ / shares	£ 0.1243129
C Ordinary shares
Disclosure of joint ventures [line items]
Par value per share (EUR/GBP per share) | € / shares		€ 0.20
A Ordinary shares
Disclosure of joint ventures [line items]
Par value per share (EUR/GBP per share) | £ / shares	£ 1
BritNed Development Limited
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
BritNed Development Limited | National Grid Interconnector Holdings Limited | C Ordinary shares
Disclosure of joint ventures [line items]
Number of shares held in joint venture (in shares)	284,500,000	284,500,000
BritNed Development Limited | National Grid Interconnector Holdings Limited | A Ordinary shares
Disclosure of joint ventures [line items]
Number of shares held in joint venture (in shares)	1	1
Joint Radio Company Limited
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
National Places LLP
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
Nemo Link Limited
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
NGET/SPT Upgrades Limited
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
NGET/SPT Upgrades Limited | National Grid Electricity Transmission plc | A Ordinary shares
Disclosure of joint ventures [line items]
Number of shares held in joint venture (in shares)	50	50
Bight Wind Holdings LLC
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	27.27%
Clean Energy Storage Systems, LLC (previously Clean Energy Generation, LLC)
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
Emerald Energy Venture LLC
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	51.00%
Island Park Energy Center, LLC
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
Islander East Pipeline Company, LLC
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
LI Energy Storage System, LLC
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
LI Solar Generation, LLC
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%
IFA2 SAS
Disclosure of joint ventures [line items]
Proportion of ownership interest in joint venture	50.00%

Subsidiary undertakings, join_5

Subsidiary undertakings, joint ventures and associates - Associates (Details)	12 Months Ended
	Mar. 31, 2022
Clean Line Energy Partners LLC
Disclosure of associates [line items]
Proportion of ownership interest in associate	32.00%
Connecticut Yankee Atomic Power Company
Disclosure of associates [line items]
Proportion of ownership interest in associate	19.50%
Direct Global Power, Inc.
Disclosure of associates [line items]
Proportion of ownership interest in associate	26.00%
Energy Impact Fund LP
Disclosure of associates [line items]
Proportion of ownership interest in associate	9.41%
KHB Venture LLC
Disclosure of associates [line items]
Proportion of ownership interest in associate	33.33%
Maine Yankee Atomic Power Company
Disclosure of associates [line items]
Proportion of ownership interest in associate	24.00%
Millennium Pipeline Company LLC
Disclosure of associates [line items]
Proportion of ownership interest in associate	26.25%
New York Transco LLC
Disclosure of associates [line items]
Proportion of ownership interest in associate	28.30%
Nysearch RMLD, LLC
Disclosure of associates [line items]
Proportion of ownership interest in associate	22.63%
The Hive IV, LLC
Disclosure of associates [line items]
Proportion of ownership interest in associate	28.20%
Yankee Atomic Electric Company
Disclosure of associates [line items]
Proportion of ownership interest in associate	34.50%
Coreso SA
Disclosure of associates [line items]
Proportion of ownership interest in associate	15.84%
Energis plc
Disclosure of associates [line items]
Proportion of ownership interest in associate	33.06%
Electralink Limited
Disclosure of associates [line items]
Proportion of ownership interest in associate	27.04%

Sensitivites - Sensitivities on

Sensitivites - Sensitivities on areas of estimation uncertainty (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Other environment related provision | Estimated future cash flows change
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Change in risk variable, percent	10.00%
Change in risk variable, impact on income statement	£ 188	£ 170
Change in risk variable, impact on net assets	188	170
UK | Actuarial assumption of discount rates
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase (decrease) in defined benefit plan expense due to reasonably possible increase (decrease) in actuarial assumption	12	4
Increase (decrease) in defined benefit obligation due to reasonably possible increase (decrease) in actuarial assumption	1,002	952
UK | Actuarial assumption of expected rates of inflation
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase (decrease) in defined benefit plan expense due to reasonably possible increase (decrease) in actuarial assumption	11	3
Increase (decrease) in defined benefit obligation due to reasonably possible increase (decrease) in actuarial assumption	733	723
UK | Actuarial assumption of expected rates of salary increases
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase (decrease) in defined benefit plan expense due to reasonably possible increase in actuarial assumption	4	1
Increase (decrease) in defined benefit obligation due to reasonably possible increase in actuarial assumption	88	42
UK | Actuarial assumption of life expectancy after retirement
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase (decrease) in defined benefit plan expense due to reasonably possible increase (decrease) in actuarial assumption	4	1
Increase (decrease) in defined benefit obligation due to reasonably possible increase (decrease) in actuarial assumption	635	612
UK | Pensions | Value of buy-in policies offset to actuarial assumption of discount rate
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Change in risk variable, impact on net assets	(164)	(257)
UK | Pensions | Value of buy-in policies offset to actuarial assumption of expected rates of inflation
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Change in risk variable, impact on net assets	(119)	(190)
UK | Pensions | Value of buy-in policies and longevity swap offset to actuarial assumption of life expectancy after retirement
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Change in risk variable, impact on net assets	£ (111)	(183)
UK | Pensions | Actuarial assumption of discount rates
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Change in actuarial assumption, percent	0.50%
UK | Pensions | Actuarial assumption of expected rates of inflation
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Change in actuarial assumption, percent	0.50%
UK | Pensions | Actuarial assumption of expected rates of salary increases
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase in actuarial assumption, percent	0.50%
UK | Pensions | Actuarial assumption of life expectancy after retirement
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase in actuarial assumption, years	1 year
US | Actuarial assumption of discount rates
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase (decrease) in defined benefit plan expense due to reasonably possible increase (decrease) in actuarial assumption	£ 16	17
Increase (decrease) in defined benefit obligation due to reasonably possible increase (decrease) in actuarial assumption	650	730
US | Actuarial assumption of expected rates of salary increases
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase (decrease) in defined benefit plan expense due to reasonably possible increase in actuarial assumption	3	3
Increase (decrease) in defined benefit obligation due to reasonably possible increase in actuarial assumption	41	42
US | Actuarial assumption of life expectancy after retirement
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase (decrease) in defined benefit plan expense due to reasonably possible increase (decrease) in actuarial assumption	3	4
Increase (decrease) in defined benefit obligation due to reasonably possible increase (decrease) in actuarial assumption	444	429
US | Assumption of US Healthcare Cost
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase (decrease) in defined benefit plan expense due to reasonably possible increase (decrease) in actuarial assumption	24	26
Increase (decrease) in defined benefit obligation due to reasonably possible increase (decrease) in actuarial assumption	£ 414	£ 437
US | Pensions | Actuarial assumption of discount rates
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Change in actuarial assumption, percent	0.50%
US | Pensions | Actuarial assumption of expected rates of salary increases
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase in actuarial assumption, percent	0.50%
US | Pensions | Actuarial assumption of life expectancy after retirement
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase in actuarial assumption, years	1 year
US | Pensions | Assumption of US Healthcare Cost
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Change in actuarial assumption, percent	1.00%

Sensitivites - Narrative (Detai

Sensitivites - Narrative (Details) - WPD £ in Millions	Mar. 31, 2022GBP (£)
Actuarial assumption of discount rates
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Sensitivity analysis, reasonably possible change in actuarial assumption	0.20%
Sensitivity analysis, actuarial assumption after reasonably possible change	5.40%
Actuarial assumption of discount rates | Decrease that would lead to an impairment
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Sensitivity analysis, reasonably possible change in actuarial assumption	0.50%
Sensitivity analysis, actuarial assumption after reasonably possible change	5.70%
Estimated value-in-use lower than carrying amount, goodwill	£ 1,033
Actuarial assumption of terminal growth rate
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Sensitivity analysis, actuarial assumption after reasonably possible change	2.00%

Sensitivites - Sensitivities _2

Sensitivites - Sensitivities on financial instruments (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Fair value change | Derivative financial instruments
Disclosure of nature and extent of risks arising from financial instruments [line items]
Change in risk variable, percent	10.00%
Change in risk variable, impact on income statement	£ (55)	£ 14
Change in risk variable, impact on net assets	£ (55)	14
Fair value change | Commodity contract derivative liabilities
Disclosure of nature and extent of risks arising from financial instruments [line items]
Change in risk variable, percent	10.00%
Change in risk variable, impact on income statement	£ 20	6
Change in risk variable, impact on net assets	£ 20	6
Inflation, UK RPI change | UK
Disclosure of nature and extent of risks arising from financial instruments [line items]
Change in risk variable, percent	0.50%
Change in risk variable, impact on income statement	£ 18	25
Change in risk variable, impact on other equity reserves	£ 0	0
Interest rate risk | UK
Disclosure of nature and extent of risks arising from financial instruments [line items]
Change in risk variable, percent	0.50%
Change in risk variable, impact on income statement	£ 41	12
Change in risk variable, impact on other equity reserves	£ 134	98
Interest rate risk | US
Disclosure of nature and extent of risks arising from financial instruments [line items]
Change in risk variable, percent	0.50%
Change in risk variable, impact on income statement	£ 4	6
Change in risk variable, impact on other equity reserves	£ 8	22
Currency risk
Disclosure of nature and extent of risks arising from financial instruments [line items]
Change in risk variable, percent	10.00%
Change in risk variable, impact on income statement	£ 43	44
Change in risk variable, impact on other equity reserves	397	285
Change in risk variable, impact on net assets	£ 1,670	1,425
Commodity price risk
Disclosure of nature and extent of risks arising from financial instruments [line items]
Change in risk variable, percent	10.00%
Increase in risk variable, impact on earnings	£ 53	20
Decrease in risk variable, impact on earnings	(54)	(21)
Increase in risk variable, impact on net assets	53	20
Decrease in risk variable, impact on net assets	£ (54)	£ (21)

Additional disclosures in res_3

Additional disclosures in respect of guaranteed securities - Narrative (Details) - GBP (£) £ in Millions	Oct. 29, 2007	Mar. 31, 2022
Disclosure of detailed information about borrowings [line items]
Proceeds from issuing shares		£ 16
National Grid plc and Niagara Mohawk Power Corporation combined
Disclosure of detailed information about borrowings [line items]
Proceeds from issuing shares		£ 29
National Grid Gas plc
Disclosure of detailed information about borrowings [line items]
Preferred shares issuance rate	3.60%
British Transco Finance Inc.
Disclosure of detailed information about borrowings [line items]
Preferred shares issuance rate	3.90%

Additional disclosures in res_4

Additional disclosures in respect of guaranteed securities - Combined Statement of Financial Position and Income Statement (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021		Mar. 31, 2020		Mar. 31, 2019
Disclosure of information about consolidated structured entities [line items]
Non-current assets	£ 76,897	£ 57,278
Current assets	17,963	9,938
Current liabilities	(24,770)	(9,368)
Non-current liabilities	(46,234)	(37,988)
Net assets	23,856	19,860
Equity	23,856	19,860		£ 19,793		£ 19,568
Revenue	18,449	13,665	[1]	13,360	[2]
Operating profit	4,371	2,401	[1]	2,279	[3]
Profit after tax from continuing operations	2,183	£ 1,304	[4]	£ 1,030	[2]
Other subsidiaries
Disclosure of information about consolidated structured entities [line items]
Non-current assets	0
Current assets	28,525
Current liabilities	(14,512)
Non-current liabilities	(2,050)
Other income from other subsidiaries	2,500
Investments in subsidiaries	14,440
National Grid plc and Niagara Mohawk Power Corporation combined
Disclosure of information about consolidated structured entities [line items]
Non-current assets	10,068
Current assets	2,431
Current liabilities	(10,276)
Non-current liabilities	(8,294)
Net assets	5,892
Equity	5,892
Revenue	2,987
Operating costs	(2,358)
Operating profit	629
Other income and costs, including taxation	(360)
Profit after tax from continuing operations	£ 2,769
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[2]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[3]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.
[4]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - WPD - GBP (£) £ in Millions	12 Months Ended		24 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Jun. 14, 2021
Disclosure of detailed information about business combination [line items]
Percentage of share capital acquired				100.00%
Cash consideration				£ 7,881
Intercompany loan payable				350
Goodwill expected to be deductible for tax purposes				0
Fair value of acquired receivables				270
Acquisition-related costs recognised	£ 95	£ 15	£ 110
Revenue of acquiree since acquisition date	1,468
Profit before tax of acquiree since acquisition date	781
Revenue of combined entity as if combination occurred at beginning of period	18,806
Profit before tax of continuing operations of combined entity as if combination occurred at beginning of period	£ 3,600
Trade receivables
Disclosure of detailed information about business combination [line items]
Fair value of acquired receivables				86
Gross contractual amounts receivable for acquired receivables				103
Best estimate at acquisition date of contractual cash flows not expected to be collected for acquired receivables				£ 17

Acquisitions (Details)

Acquisitions (Details) - GBP (£) £ in Millions	Jun. 14, 2021	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020		Mar. 31, 2019
Non-current assets
Property, plant and equipment		£ 57,532	£ 47,043
Other intangible assets		3,272	1,443
Pension assets		3,885	1,747
Other non-current assets		303	293
Total non-current assets		76,897	57,278
Current assets
Trade and other receivables		3,715	2,919
Financial and other investments		3,145	2,342	£ 1,998		£ 1,981
Cash and cash equivalents		204	157	£ 73	[1]	£ 252	[1]
Total current assets		17,963	9,938
Total assets		94,860	67,216
Current liabilities
Borrowings		(12,121)	(3,737)
Trade and other payables		(4,915)	(3,517)
Total current liabilities		(24,770)	(9,368)
Non-current liabilities
Borrowings		(33,344)	(27,483)
Deferred tax liabilities		(6,765)	(4,815)
Non-current		(1,342)	(1,094)
Other non-current liabilities		(805)	(843)
Total non-current liabilities		(46,234)	(37,988)
Total liabilities		(71,004)	(47,356)
Net assets		23,856	19,860
Goodwill		£ 9,532	£ 4,588
WPD
Non-current assets
Property, plant and equipment	£ (4,026)
Other intangible assets	1,714
Pension assets	164
Total non-current assets	(2,148)
Total assets	(2,148)
Current liabilities
Trade and other payables	48
Total current liabilities	48
Non-current liabilities
Borrowings	(1,589)
Deferred tax	224
Contract liabilities	2,706
Other non-current liabilities	(21)
Total non-current liabilities	1,320
Total liabilities	1,368
Total identifiable net assets	(780)
Goodwill	3,467
Total consideration transferred	2,687
Non-current assets
Property, plant and equipment	10,051
Other intangible assets	1,763
Pension assets	566
Other non-current assets	27
Total non-current assets	12,407
Current assets
Trade and other receivables	268
Financial and other investments	69
Cash	44
Other current assets	42
Total current assets	423
Total assets	12,830
Current liabilities
Borrowings	(730)
Trade and other payables	(483)
Other current liabilities	(35)
Total current liabilities	(1,248)
Non-current liabilities
Borrowings	(7,556)
Deferred tax	(789)
Contract liabilities	0
Other non-current liabilities	(77)
Total non-current liabilities	(8,422)
Total liabilities	(9,670)
Total identifiable net assets	3,160
Goodwill	4,721
Total consideration transferred	7,881
Cash consideration	7,881
WPD | WPD
Non-current assets
Property, plant and equipment	14,077
Other intangible assets	49
Pension assets	402
Other non-current assets	27
Total non-current assets	14,555
Current assets
Trade and other receivables	268
Financial and other investments	69
Cash and cash equivalents	44
Other current assets	42
Total current assets	423
Total assets	14,978
Current liabilities
Borrowings	(730)
Trade and other payables	(531)
Other current liabilities	(35)
Total current liabilities	(1,296)
Non-current liabilities
Borrowings	(5,967)
Deferred tax liabilities	(1,013)
Non-current	(2,706)
Other non-current liabilities	(56)
Total non-current liabilities	(9,742)
Total liabilities	(11,038)
Net assets	3,940
Goodwill	1,254
Total consideration transferred	£ 5,194
[1]	Comparative amounts have been re-presented to reflect the classification of the UK Gas Transmission business as a discontinued operation. See notes 1 and 10 for further information.

Post balance sheet events - Nar

Post balance sheet events - Narrative (Details) £ in Millions	May 11, 2022GBP (£)
Entering into significant commitments or contingent liabilities | Interconnector revenue
Subsequent Event1 [Line Items]
Refunds provision	£ 200