NuCana (NCNA) 6-K 14 May 19 2019 Q1 Unaudited Condensed Consolidated Statements of Operations Financial data

Document and Entity Information

Document and Entity Information	3 Months Ended
	Mar. 31, 2019
Document and entity information [abstract]
Document Type	6-K
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	NCNA
Entity Registrant Name	NUCANA PLC
Entity Central Index Key	0001709626
Current Fiscal Year End Date	--12-31

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Statements of Operations - GBP (£) £ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Profit or loss [abstract]
Research and development expenses	£ (4,350)	£ (3,705)
Administrative expenses	(1,346)	(1,240)
Net foreign exchange losses	(979)	(2,548)
Operating loss	(6,675)	(7,493)
Finance income	318	190
Loss before tax	(6,357)	(7,303)
Income tax credit	1,000	909
Loss for the period	£ (5,357)	£ (6,394)
Basic and diluted loss per share	£ (0.17)	£ (0.20)

Unaudited Condensed Consolida_2

Unaudited Condensed Consolidated Statements of Comprehensive Loss - GBP (£) £ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of comprehensive income [abstract]
Loss for the period	£ (5,357)	£ (6,394)
Items that may be reclassified subsequently to profit or loss:
Exchange differences on translation of foreign operations	(5)	(5)
Other comprehensive expense for the period	(5)	(5)
Total comprehensive loss for the period	(5,362)	(6,399)
Attributable to:
Equity holders of the Company	£ (5,362)	£ (6,399)

Unaudited Condensed Consolida_3

Unaudited Condensed Consolidated Statements of Financial Position - GBP (£) £ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Non-current assets
Intangible assets	£ 3,324	£ 3,122
Property, plant and equipment	947	427
Deferred tax asset	39	47
Total non-current assets	4,310	3,596
Current assets
Prepayments, accrued income and other receivables	2,739	2,354
Current income tax receivable	5,269	4,263
Cash and cash equivalents	69,908	76,972
Total current assets	77,916	83,589
Total assets	82,226	87,185
Capital and reserves
Share capital and share premium	80,749	80,715
Other reserves	60,018	59,692
Accumulated deficit	(64,117)	(58,813)
Total equity attributable to equity holders of the Company	76,650	81,594
Non-current liabilities
Provisions	26	26
Lease liability	341
Total non-current liabilities	367	26
Current liabilities
Trade payables	2,258	2,455
Payroll taxes and social security	111	127
Lease liability	188
Accrued expenditure	2,652	2,983
Total current liabilities	5,209	5,565
Total liabilities	5,576	5,591
Total equity and liabilities	£ 82,226	£ 87,185

Unaudited Condensed Consolida_4

Unaudited Condensed Consolidated Statements of Changes In Equity - GBP (£) £ in Thousands	Total	Share Capital [member]	Share Premium [member]	Own Share Reserve [member]	Share Option Reserve [member]	Foreign Currency Translation Reserve [member]	Capital Reserve [member]	Accumulated Deficit [member]
Beginning balance at Dec. 31, 2017	£ 93,420	£ 1,272	£ 79,236	£ (339)	£ 15,955	£ (11)	£ 42,466	£ (45,159)
Loss for the period	(6,394)							(6,394)
Other comprehensive expense for the period	(5)					(5)
Total comprehensive loss for the period	(6,399)					(5)		(6,394)
Share-based payments	428				428
Ending balance at Mar. 31, 2018	87,449	1,272	79,236	(339)	16,383	(16)	42,466	(51,553)
Beginning balance at Dec. 31, 2018	81,594	1,289	79,426	(339)	17,564	1	42,466	(58,813)
Loss for the period	(5,357)							(5,357)
Other comprehensive expense for the period	(5)					(5)
Total comprehensive loss for the period	(5,362)					(5)		(5,357)
Share-based payments	384				384
Exercise of share options	34	1	33		(53)			53
Ending balance at Mar. 31, 2019	£ 76,650	£ 1,290	£ 79,459	£ (339)	£ 17,895	£ (4)	£ 42,466	£ (64,117)

Unaudited Condensed Consolida_5

Unaudited Condensed Consolidated Statements of Cash Flows - GBP (£) £ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities
Loss for the period	£ (5,357)	£ (6,394)
Adjustments for:
Income tax credit	(1,000)	(909)
Amortization and depreciation	161	74
Finance income	(318)	(190)
Share-based payments	384	428
Net foreign exchange losses	984	2,537
Cash flows from (used in) operations before changes in working capital	(5,146)	(4,454)
Movements in working capital:
Increase in prepayments, accrued income and other receivables	(402)	197
Decrease in trade payables	(197)	(222)
Decrease in payroll taxes, social security and accrued expenditure	(347)	(190)
Movements in working capital	(946)	(215)
Cash used in operations	(6,092)	(4,669)
Net income tax credit		1,910
Net cash used in operating activities	(6,092)	(2,759)
Cash flows from investing activities
Interest received	311	202
Payments for property, plant and equipment	(18)	(171)
Payments for intangible assets	(280)	(136)
Net cash generated from (used in) investing activities	13	(105)
Cash flows from financing activities
Payments for lease liabilities	(40)
Proceeds from issue of share capital	34
Net cash used in financing activities	(6)
Net decrease in cash and cash equivalents	(6,085)	(2,864)
Cash and cash equivalents at beginning of period	76,972	86,703
Foreign currency translation differences	(979)	(2,501)
Cash and cash equivalents at end of period	£ 69,908	£ 81,338

General information

General information	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
General information	1. General information NuCana plc (“NuCana” or the “Company”) is a clinical-stage biopharmaceutical company developing a portfolio of new medicines to treat cancer. NuCana is harnessing the power of phosphoramidate chemistry to generate new medicines called ProTides. These compounds have the potential to improve cancer treatment by enhancing the efficacy and safety of several current standards of care. The Company has ordinary shares in the form of American Depositary Shares (“ADSs”) registered with the US Securities and Exchange Commission (the “SEC”) and has been listed on The Nasdaq Global Market (“Nasdaq”) since October 2, 2017. The Company is incorporated in England and Wales and domiciled in the United Kingdom. The Company’s registered office is located at 77/78 Cannon Street, London EC4N 6AF, United Kingdom and its principal place of business is located at 3 Lochside Way, Edinburgh, EH12 9DT, United Kingdom. The Company has two wholly owned subsidiaries, NuCana, Inc. and NuCana BioMed Trustee Company Limited (together referred to as the “Group”). The comparative figures for the three months ended March 31, 2018 and at December 31, 2018 are not the Group’s statutory accounts for that financial year within the meaning of section 434 of the Companies Act 2006. Those accounts have not yet been reported on by the Company’s auditor or delivered to the Registrar of Companies. The Company filed its Annual Report on Form 20-F

Significant accounting policies

Significant accounting policies	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Significant accounting policies	2. Significant accounting policies Basis of preparation The unaudited condensed consolidated financial statements (the “financial statements”) for the three months ended March 31, 2019 have been prepared in accordance with International Accounting Standard 34, “Interim Financial Reporting” Leases The financial statements do not include all the information and disclosures required in the annual financial statements, and should be read in conjunction with the Company’s annual financial statements for the year ended December 31, 2018. In the opinion of management, these condensed consolidated financial statements include all normal recurring adjustments necessary for a fair statement of the results of operations, financial position and cash flows. The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results that can be expected for the Company’s fiscal year ending December 31, 2019. Adoption of IFRS 16: Leases IFRS 16 was issued in January 2016 and replaces IAS 17 Leases Determining Whether an Arrangement Contains a Lease SIC-15 Operating Leases-Incentives SIC-27 Evaluating the Substance of Transactions Involving the Legal Form of a Lease Upon adoption of IFRS 16 the Company recognized right of use lease assets in the amount of £0.5 million and corresponding lease liabilities of £0.4 million. The adoption of IFRS 16 has not had a material impact on the reported loss for the period. Going concern In common with many companies in the biopharmaceutical sector, the Company incurs significant expenditure in its early years as it researches and develops its potential products for market. The Company’s board of directors, having reviewed the operating budgets and development plans, considers that the Company has adequate resources to continue in operation for the foreseeable future. The board of directors is therefore satisfied that it is appropriate to adopt the going concern basis of accounting in preparing the financial statements. The Company believes that its cash and cash equivalents of £69.9 million at March 31, 2019 will be sufficient to fund its current operating plan for at least the next 12 months. As the Company continues to incur losses, the transition to profitability is dependent upon the successful development, approval and commercialization of its product candidates and achieving a level of revenues adequate to support its cost structure. The Company may never achieve profitability, and unless and until it does, it will continue to need to raise additional capital. There can be no assurances, however, that additional funding will be available on acceptable terms. Judgements and estimates The accounting estimates and judgements made by management in applying the Group’s accounting policies that have the most significant effect on the amounts included within these financial statements, were the same as those that applied to the annual financial statements for the year ended December 31, 2018.

Income tax

Income tax	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Income tax	3. Income tax For the Three Months Ended 2019 2018 (in thousands) £ £ Current tax: In respect of current period U.K. 1,007 948 In respect of current period U.S. (1 ) 1 1,006 949 Deferred tax: In respect of current period U.S. (6 ) — In respect of prior period U.S. — (40 ) Income tax credit 1,000 909 The income tax credit recognized primarily represents the U.K. research and development tax credit. In the United Kingdom, the Company is able to surrender some of its losses for a cash rebate of up to 33.35% of expenditure related to eligible research and development projects. March 31, December 31, (in thousands) £ £ Current income tax receivable U.K. tax 5,246 4,239 U.S. tax 23 24 5,269 4,263 Deferred tax asset U.S. deferred tax asset 39 47

Basic and diluted loss per shar

Basic and diluted loss per share	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Basic and diluted loss per share	4. Basic and diluted loss per share For the Three Months Ended 2019 2018 (in thousands, except per share data) £ £ Loss for the period (5,357 ) (6,394 ) Basic and diluted weighted average number of shares 32,227 31,811 £ £ Basic and diluted loss per share (0.17 ) (0.20 ) Basic loss per share is calculated by dividing the loss for the period attributable to the equity holders of the Company by the weighted average number of shares outstanding during the period. The potential shares issued through equity settled transactions were considered to be anti-dilutive as they would have decreased the loss per share and were therefore excluded from the calculation of diluted loss per share.

Intangible assets

Intangible assets	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Intangible assets	5. Intangible assets Intangible assets comprise patents with a carrying value of £3.2 million as of March 31, 2019 (as of December 31, 2018: £3.0 million) and computer software with a carrying value of £0.1 million as of March 31, 2019 (as of December 31, 2018: £0.1 million). During the three months ended March 31, 2019, the Company acquired intangible assets with a cost of £0.3 million in relation to patents. There were no disposals of intangible assets in the three months ended March 31, 2019.

Cash and cash equivalents

Cash and cash equivalents	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Cash and cash equivalents	6. Cash and cash equivalents March 31, December 31, (in thousands) £ £ Cash and cash equivalents 69,908 76,972 Cash and cash equivalents comprise cash at bank with maturities of three months or less and earn interest at fixed or variable rates based on the terms agreed for each account.

Share-based payments

Share-based payments	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Share-based payments	7. Share-based payments The Company has three share-based payment plans for employees, directors and consultants. The share options granted will be settled in equity. During the three months ended March 31, 2019, 120,750 share options were granted under the Company’s U.K. share-based payment plans as detailed in the table below. Options granted under these plans will vest if the option holder remains under respective contract of employment or contract of service for the agreed vesting period. The share options granted under these plans will vest equally over a period of four years. The fair values of options granted were determined using the Black-Scholes model that takes into account factors specific to the share incentive plan. As the Company completed its initial public offering in October 2017, it is not possible to derive historical volatility from the Company’s ADSs prior to October 2017. The underlying expected volatility was therefore determined by using the historical volatility of similar listed entities as a proxy. The volatility percentage applied to each tranche is the average of the historical volatility of comparable companies to the Company. The following weighted average principal assumptions were used in calculating the fair values of options granted: Options granted on Mar 13, 2019 Vesting dates Mar 13, 2020 Mar 13, 2021 Mar 13, 2022 Mar 13, 2023 Volatility 69.05 % Dividend yield 0 % Risk-free investment rate 0.85 % Fair value of option at grant date £ 5.46 Fair value of share at grant date £ 10.13 Exercise price at date of grant £ 10.13 Lapse date Mar 13, 2029 Expected option life (years) 4.50 Number of options granted 120,750 For the three months ended March 31, 2019, the Company has recognized £0.4 million of share-based payment expense in the statement of operations (three months ended March 31, 2018: £0.4 million).

Share capital and share premium

Share capital and share premium	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Share capital and share premium	8. Share capital and share premium March 31, December 31, (in thousands) £ £ Share capital 1,290 1,289 Share premium 79,459 79,426 80,749 80,715 March 31, December 31, Number (in thousands) Issued share capital comprises: Ordinary shares of £0.04 each 32,236 32,226 Number of Share Share (in thousands) Fully paid shares: £ £ Balance at December 31, 2018 32,226 1,289 79,426 Issue of shares on exercise of options 10 1 33 Balance at March 31, 2019 32,236 1,290 79,459

Contingent liabilities

Contingent liabilities	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Contingent liabilities	9. Contingent liabilities Under its U.K. share-based payment plan, the Company granted unapproved share options that have fully vested. If and when these share options are exercised, the Company will be liable for the Employer Class 1 National Insurance payable to HMRC in the United Kingdom. This contingent liability will be determined based on the market value of the shares on exercise less the exercise price paid by the option holders, at the prevailing rate of Employer National Insurance (currently 13.8%). Based on the closing price of the Company’s ADSs on the Nasdaq Global Select Market on March 31, 2019, the last trading day of the period to which these financial statements relate, and assuming full exercise of all outstanding and vested unapproved share options on that date, the Employer National Insurance contingent liability would have been £3.8 million (December 31, 2018: £3.3 million).

Significant accounting polici_2

Significant accounting policies (Policies)	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Basis of preparation	Basis of preparation The unaudited condensed consolidated financial statements (the “financial statements”) for the three months ended March 31, 2019 have been prepared in accordance with International Accounting Standard 34, “Interim Financial Reporting” Leases The financial statements do not include all the information and disclosures required in the annual financial statements, and should be read in conjunction with the Company’s annual financial statements for the year ended December 31, 2018. In the opinion of management, these condensed consolidated financial statements include all normal recurring adjustments necessary for a fair statement of the results of operations, financial position and cash flows. The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results that can be expected for the Company’s fiscal year ending December 31, 2019.
Going concern	Going concern In common with many companies in the biopharmaceutical sector, the Company incurs significant expenditure in its early years as it researches and develops its potential products for market. The Company’s board of directors, having reviewed the operating budgets and development plans, considers that the Company has adequate resources to continue in operation for the foreseeable future. The board of directors is therefore satisfied that it is appropriate to adopt the going concern basis of accounting in preparing the financial statements. The Company believes that its cash and cash equivalents of £69.9 million at March 31, 2019 will be sufficient to fund its current operating plan for at least the next 12 months. As the Company continues to incur losses, the transition to profitability is dependent upon the successful development, approval and commercialization of its product candidates and achieving a level of revenues adequate to support its cost structure. The Company may never achieve profitability, and unless and until it does, it will continue to need to raise additional capital. There can be no assurances, however, that additional funding will be available on acceptable terms.
Judgements and estimates	Judgements and estimates The accounting estimates and judgements made by management in applying the Group’s accounting policies that have the most significant effect on the amounts included within these financial statements, were the same as those that applied to the annual financial statements for the year ended December 31, 2018.

Income tax (Tables)

Income tax (Tables)	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Schedule of Major Components of Income Tax	For the Three Months Ended 2019 2018 (in thousands) £ £ Current tax: In respect of current period U.K. 1,007 948 In respect of current period U.S. (1 ) 1 1,006 949 Deferred tax: In respect of current period U.S. (6 ) — In respect of prior period U.S. — (40 ) Income tax credit 1,000 909 March 31, December 31, (in thousands) £ £ Current income tax receivable U.K. tax 5,246 4,239 U.S. tax 23 24 5,269 4,263 Deferred tax asset U.S. deferred tax asset 39 47

Basic and diluted loss per sh_2

Basic and diluted loss per share (Tables)	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Schedule of Basic and Diluted Loss Per Share	For the Three Months Ended 2019 2018 (in thousands, except per share data) £ £ Loss for the period (5,357 ) (6,394 ) Basic and diluted weighted average number of shares 32,227 31,811 £ £ Basic and diluted loss per share (0.17 ) (0.20 )

Cash and cash equivalents (Tabl

Cash and cash equivalents (Tables)	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Schedule of Cash and Cash Equivalents	March 31, December 31, (in thousands) £ £ Cash and cash equivalents 69,908 76,972

Share-based payments (Tables)

Share-based payments (Tables)	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Summary of Principal Assumptions Used for Valuation of Share Options	The following weighted average principal assumptions were used in calculating the fair values of options granted: Options granted on Mar 13, 2019 Vesting dates Mar 13, 2020 Mar 13, 2021 Mar 13, 2022 Mar 13, 2023 Volatility 69.05 % Dividend yield 0 % Risk-free investment rate 0.85 % Fair value of option at grant date £ 5.46 Fair value of share at grant date £ 10.13 Exercise price at date of grant £ 10.13 Lapse date Mar 13, 2029 Expected option life (years) 4.50 Number of options granted 120,750

Share capital and share premi_2

Share capital and share premium (Tables)	3 Months Ended
	Mar. 31, 2019
Text block [abstract]
Summary of Share Capital and Share Premium	March 31, December 31, (in thousands) £ £ Share capital 1,290 1,289 Share premium 79,459 79,426 80,749 80,715 March 31, December 31, Number (in thousands) Issued share capital comprises: Ordinary shares of £0.04 each 32,236 32,226
Summary of Movement in the Share Capital	Number of Share Share (in thousands) Fully paid shares: £ £ Balance at December 31, 2018 32,226 1,289 79,426 Issue of shares on exercise of options 10 1 33 Balance at March 31, 2019 32,236 1,290 79,459

General Information - Additiona

General Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019Subsidiary
Disclosure Of General Information About Financial Statements [abstract]
Description of nature of entity's operations	Clinical-stage biopharmaceutical company developing a portfolio of new medicines to treat cancer
Name of reporting entity	NuCana plc
Domicile of entity	United Kingdom
Country of incorporation	England and Wales
Number of subsidiaries	2
Name of subsidiary	NuCana, Inc. and NuCana BioMed Trustee Company Limited.

Significant Accounting Polici_3

Significant Accounting Policies - Additional Information (Detail) - GBP (£) £ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Disclosure of summary of significant accounting policies [abstract]
Right of use lease assets	£ 500
Lease liabilities	400
Cash and cash equivalents	£ 69,908	£ 76,972	£ 81,338	£ 86,703

Income Tax - Schedule of Major

Income Tax - Schedule of Major Components of Income Tax Credit (Detail) - GBP (£) £ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Current tax:
Total current tax	£ 1,006	£ 949
Deferred tax:
Income tax credit	1,000	909
U.K. [member]
Current tax:
In respect of current period	1,007	948
U.S. [member]
Current tax:
In respect of current period	(1)	1
Deferred tax:
In respect of current period	£ (6)
In respect of prior period		£ (40)

Income Tax - Additional Informa

Income Tax - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019
U.K. [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Percentage of losses surrendered for R&D tax credit	33.35%

Income Tax - Schedule of Majo_2

Income Tax - Schedule of Major Components of Income Tax Assets (Detail) - GBP (£) £ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current income tax receivable
Current income tax receivable	£ 5,269	£ 4,263
Deferred tax asset
Deferred tax asset	39	47
U.K. [member]
Current income tax receivable
Current income tax receivable	5,246	4,239
U.S. [member]
Current income tax receivable
Current income tax receivable	23	24
Deferred tax asset
Deferred tax asset	£ 39	£ 47

Basic and Diluted Loss per Sh_3

Basic and Diluted Loss per Share - Schedule of Basic and Diluted Loss Per Share (Detail) - GBP (£) £ / shares in Units, £ in Thousands, shares in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings per share [abstract]
Loss for the period	£ (5,357)	£ (6,394)
Basic and diluted weighted average number of shares	32,227	31,811
Basic and diluted loss per share	£ (0.17)	£ (0.20)

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - GBP (£)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Disclosure of detailed information about intangible assets [line items]
Intangible assets, carrying value	£ 3,324,000	£ 3,122,000
Patents [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets, carrying value	3,200,000	3,000,000
Intangible assets, acquired	300,000
Computer Software [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets, carrying value	100,000	£ 100,000
Intangible assets, acquired	£ 0

Cash and Cash Equivalents - Sch

Cash and Cash Equivalents - Schedule of Detailed Information About Cash and Cash Equivalents (Detail) - GBP (£) £ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Cash and cash equivalents [abstract]
Cash and cash equivalents	£ 69,908	£ 76,972	£ 81,338	£ 86,703

Share Based Payments - Addition

Share Based Payments - Additional Information (Detail) £ in Millions	3 Months Ended
	Mar. 31, 2019GBP (£)	Mar. 31, 2018GBP (£)
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based payment expense	£ 0.4	£ 0.4
U.K. Share-Based Payment Plans [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of share options granted in share-based payment arrangement	120,750
Share options granted, vesting period	4 years

Share Based Payments - Summary

Share Based Payments - Summary of Principal Assumptions used for Valuation of Share Options (Detail) - 2019 Share Options [member] - Grant Date March 13, 2019 [member]	3 Months Ended
	Mar. 31, 2019GBP (£)sharesyr
Disclosure of terms and conditions of share-based payment arrangement [line items]
Volatility	69.05%
Dividend yield	0.00%
Risk-free investment rate	0.85%
Fair value of option at grant date	£ 5.46
Fair value of share at grant date	10.13
Exercise price at date of grant	£ 10.13
Lapse date	Mar. 13, 2029
Expected option life (years) | yr	4.50
Number of options granted | shares	120,750
Vesting Dates One [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting dates	Mar. 13, 2020
Vesting Dates Two [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting dates	Mar. 13, 2021
Vesting Dates Three [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting dates	Mar. 13, 2022
Vesting Dates Four [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting dates	Mar. 13, 2023

Share Capital and Share Premi_3

Share Capital and Share Premium - Summary of Share Capital and Share Premium (Detail) - GBP (£) £ in Thousands, shares in Thousands	Mar. 31, 2019	Dec. 31, 2018
Disclosure of classes of share capital [abstract]
Share capital	£ 1,290	£ 1,289
Share premium	79,459	79,426
Share capital and share premium	£ 80,749	£ 80,715
Ordinary shares of £0.04 each	32,236	32,226

Share Capital and Share Premi_4

Share Capital and Share Premium - Summary of Share Capital and Share Premium (Parenthetical) (Detail) - £ / shares	Mar. 31, 2019	Dec. 31, 2018
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Par value per share	£ 0.04	£ 0.04

Share Capital and Share Premi_5

Share Capital and Share Premium - Summary of Movement in the Share Capital (Detail) £ in Thousands, shares in Thousands	3 Months Ended
	Mar. 31, 2019GBP (£)shares
Disclosure of classes of share capital [line items]
Beginning balance, Shares | shares	32,226
Issue of shares on exercise of options | shares	10
Ending balance, Shares | shares	32,236
Beginning balance	£ 81,594
Issue of shares on exercise of options	34
Ending balance	76,650
Share Capital [member]
Disclosure of classes of share capital [line items]
Beginning balance	1,289
Issue of shares on exercise of options	1
Ending balance	1,290
Share Premium [member]
Disclosure of classes of share capital [line items]
Beginning balance	79,426
Issue of shares on exercise of options	33
Ending balance	£ 79,459

Contingent Liabilities - Additi

Contingent Liabilities - Additional Information (Detail) - GBP (£) £ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Disclosure of contingent liabilities [abstract]
Employer national insurance contingent liability	£ 3.8	£ 3.3
Prevailing rate of employer national insurance	13.80%