Exhibit 99.1

nationalgrid                                                    KEYSPAN

For Immediate Release
- ---------------------

                        NATIONAL GRID TO ACQUIRE KEYSPAN
                        IN $7.3 BILLION CASH TRANSACTION

   Acquisition Will Create The Third-Largest Energy Delivery Utility In The US

                     Excellent Strategic and Operational Fit

            National Grid To Maintain Significant Corporate Presence
                 In Massachusetts, Brooklyn And Upstate New York

         Westborough, Mass. and Brooklyn, New York, February 27, 2006 -

     National Grid (LSE: NG., NYSE:  NGG) and KeySpan  Corporation  (NYSE:  KSE)
today  announced a definitive  agreement  under which National Grid will acquire
KeySpan for $42.00 per share in cash.  The terms of the agreement  value KeySpan
at approximately  $7.3 billion,  with an enterprise value of $11.8 billion.  The
boards of both companies  unanimously approved the acquisition.  The transaction
materially  expands the size of National  Grid's US  operations  and creates the
third-largest  energy delivery utility in the United States,  with well balanced
electricity and gas businesses serving nearly eight million customers in the New
York State and New England regions.

     "KeySpan  is an  excellent  operational  and  geographic  fit and a natural
extension of our business and our  strategy,"  said Roger Urwin,  National  Grid
Group Chief  Executive.  "KeySpan is an  acquisition  which makes sense at every
level and we look  forward to its  completion  and to welcoming  Robert  Catell,
KeySpan's Chairman and Chief Executive Officer, to our Board."

     Said Steve Holliday,  Chief Executive  Designate of National Grid, "KeySpan
is a high quality business with significant  growth  prospects.  The acquisition
provides  us with an  excellent  opportunity  to  combine  our core  operational
expertise  with that of KeySpan,  while  continuing to provide safe and reliable
service to customers.  National Grid and KeySpan customers will benefit by being
served by a larger, stronger company that is focused on energy delivery, and has
a growing presence and strategic commitment to the region."

     Michael E.  Jesanis will remain Chief  Executive  Officer of National  Grid
USA. Robert B. Catell,  will become Executive  Chairman of National Grid USA and
Deputy Chairman of National Grid plc.





     Holliday  continued,  "Bob is a highly  respected  and superb leader with a
strong track record in  delivering  growth,  while  maintaining a sharp focus on
customer satisfaction."

     Said Robert B.  Catell,  Chairman and Chief  Executive  Officer of KeySpan,
"This  transaction will deliver  significant value to shareholders and customers
of both  companies.  KeySpan will become an important part of one of the largest
and most efficient  energy delivery  companies in the world,  and have access to
additional financial resources to invest in our energy infrastructure and growth
opportunities. Together, we can create an even more efficient company focused on
controlling  delivery costs and enhancing  customer  service.  Further,  we will
continue to work with state  regulators to structure  long-term  rate plans that
benefit  customers and shareholders and include  incentives for cost control and
superior customer service."

     Michael E. Jesanis,  President and Chief Executive Officer of National Grid
USA, said, "National Grid and KeySpan have much in common,  including a talented
and diverse  workforce with proud traditions  extending back over a century.  We
share a core business of energy  delivery - both gas and electricity - and serve
many of the same communities in Massachusetts,  as well as customers in New York
and New Hampshire.  We will be working closely together on integration  planning
that will enable our companies to come together  seamlessly once the transaction
closes and we look forward to a smooth transition for our customers and those of
the Long Island Power Authority (LIPA)."

     KeySpan operates LIPA's transmission and distribution system under contract
to LIPA. LIPA is a non-profit  electric utility,  which owns the retail electric
system on Long  Island and  provides  electric  service  to nearly  1.1  million
customers in Nassau and Suffolk counties,  and the Rockaway Peninsula in Queens,
NY.  KeySpan and LIPA  recently  agreed to extend  their  existing  relationship
through 2013.

         Upon completion of the transaction, KeySpan will become a wholly owned
subsidiary of National Grid and will continue to operate as KeySpan. National
Grid will continue to have customer-focused operations throughout its four-state
service territory (Massachusetts, New Hampshire, New York and Rhode Island) and
will maintain a significant corporate presence in Massachusetts, Brooklyn, NY
and Upstate New York, as well as an operations center in Hicksville, NY.


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         National Grid will honor all labor agreements in effect with the
KeySpan unions. Plans on combining operations, facilities and functions,
including determination of the impact on total number of jobs, will be developed
over the next year. Employee reductions are expected to be achieved through
attrition and voluntary programs across the combined company.

     Both  companies  have  excellent  records  of  corporate   citizenship  and
community involvement,  and National Grid has committed to maintain the historic
level of support in KeySpan's service territory.

     The transaction is subject to customary closing  conditions,  including the
approval  of the  shareholders  of both  companies,  certain  federal  and state
regulatory  approvals  and  clearance  under  the  Hart-Scott-Rodino   Act.  The
transaction is targeted to close by early 2007.

     KeySpan  is the fifth  largest  distributor  of  natural  gas in the United
States  and the  largest in the  Northeast,  and is one of the  fastest  growing
distributors  in the country.  The  company's  investments  in gas pipelines and
storage will enable National Grid to take advantage of a broader range of future
opportunities in the US. KeySpan's uniquely positioned and attractive generation
assets  provide  power to New York City's load  serving  entities and LIPA under
long  term  contracts.  National  Grid  has no  current  plans  to  divest  this
portfolio.

     Rothschild is serving as financial advisor to National Grid. Skadden, Arps,
Slate,  Meagher & Flom LLP is serving as legal advisor to National Grid.  Lazard
and  Simpson  Thacher & Bartlett  LLP served as  financial  and legal  advisors,
respectively, to KeySpan.

About National Grid

     National Grid is an international  energy delivery  business with principal
activities in the regulated electricity and natural gas industries. In the U.S.,
National Grid transmits and distributes  electricity and natural gas to nearly 4
million  customers across 29,000 square miles of  Massachusetts,  New Hampshire,
New York and Rhode Island.

     KeySpan  is  National  Grid's  fifth  US  acquisition.  Previously,  it had
acquired New England Electric System and Eastern  Utilities  Associates  (2000),
and Niagara Mohawk (2002).  Earlier this month,  National Grid announced that it
will  acquire the Rhode  Island gas  distribution  business  of  Southern  Union
Company.

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     The  company  owns the  high-voltage  electricity  transmission  network in
England and Wales and operates the system across Great Britain. It also owns and
operates the high-pressure  gas transmission  system in Britain and, through its
natural gas  distribution  business  serves over 11 million  meters in homes and
businesses in Britain. In addition,  it has a number of businesses  operating in
related areas such as LNG importation, wireless infrastructure for broadcast and
telecommunications, property, metering and interconnectors.

About KeySpan

     A member  of the  Standard  & Poor's  500  Index,  KeySpan  is the  largest
distributor of natural gas in the Northeast,  operating  regulated gas utilities
in New York, Massachusetts,  and New Hampshire that serve 2.6 million customers.
These  customer-focused  businesses are  complemented  by a portfolio of service
companies that offer energy-related  products,  services, and solutions to homes
and  businesses.  KeySpan is also the  largest  electric  generator  in New York
State, with approximately  6,650 megawatts of generating  capacity that provides
power to 1.1 million customers of the Long Island Power Authority (LIPA) on Long
Island and supplies  approximately 25 percent of New York City's capacity needs.
KeySpan also operates LIPA's transmission and distribution system under contract
to LIPA.  In addition to these  assets,  KeySpan has  strategic  investments  in
pipeline  transportation,  distribution,  storage,  and production.  KeySpan has
headquarters in Brooklyn,  New England,  and Long Island.  For more information,
visit KeySpan's web site at: http://www.keyspanenergy.com.

Important Information

     In connection with the proposed merger, KeySpan will file a proxy statement
with the Securities and Exchange Commission.  INVESTORS AND SECURITY HOLDERS ARE
ADVISED  TO READ THE  PROXY  STATEMENT  WHEN IT  BECOMES  AVAILABLE,  AS IT WILL
CONTAIN IMPORTANT INFORMATION.  Investors and security holders may obtain a free
copy of the  proxy  statement,  when  available,  and other  documents  filed by
KeySpan   at  the   Securities   and   Exchange   Commission's   web   site   at
http://www.sec.gov.  KeySpan and its  directors,  executive  officers  and other
members of its management and employees may be deemed to be  participants in the
solicitation  of proxies from its  stockholders  in connection with the proposed
merger.  Information  concerning the interests of KeySpan's  participants in the
solicitation is set forth in KeySpan's proxy statement and Annual Report on Form
10-K filed (filed with the Securities and Exchange  Commission on March 30, 2005
and March 2, 2005,  respectively)  and will be set forth in the proxy  statement
relating to the merger when it becomes available.

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UK Analyst/Investor Conference Call Information:

National  Grid plc will conduct an  analyst/investor  call at 9:30 a.m.  (London
time) 4:30 a.m.  (EST)  regarding  the  transaction.  To access the event,  dial
1-866-432-7186  (international  calls  dial  011 44 20  7081  9429)  or  link to
www.ngrid.com.  A replay of the  analyst/investor  call will be available  until
March 13,  2006 by dialing 011 44 20 7081 9440 and  entering  access code 869448
and recording number 355761.  There will also be a debt investor conference call
at 12:00 p.m. (London time). To access the event, dial 011 44 20 7162 0025.

Brooklyn, NY and Boston, MA Press Conferences Information:

National Grid and KeySpan will hold press conferences today in Brooklyn,  NY and
Boston, MA to discuss the transaction. The Brooklyn, NY press conference will be
held at 10:00 a.m. (EST) at the Company's  headquarters,  One MetroTech  Center,
Brooklyn,  NY. To access the event, dial 1-866-425-6191  (international  callers
dial  1-973-935-2981) and use passcode 7087138. A replay of the press conference
will be  available  for 30 days.  To  access  the  replay,  dial  1-877-519-4471
(International  callers dial  1-973-341-3080)  and enter passcode  7087138.  The
event           will           also          be           available           on
http://nationalgridkeyspan.acquisitionannouncement.com.

The Boston press conference will be held at 3:00 p.m. (EST) at the Westin Copley
Place, 10 Huntington Avenue, Boston, MA.

B-roll Information:

Satellite  feed  containing  b-roll footage of National Grid and KeySpan will be
available for downlink as follows:

Today, Monday February 27, 2006

04:00-04:15 EST
AMC 1 / (C) band tr. 22 ANALOG
d/l freq: 4140 Horizontal

 13:00-13:15 EST (1pm-1:15PM)
AMC 1 / (C) band tr. 22 ANALOG
d/l freq: 4140 Horizontal

This feed is free for unrestricted use.


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Media Contacts:

National Grid                                         KeySpan

Denise DesChenes/Jonathan Gasthalter/                 Jody Fisher
Susan Burns                                           Manager Media Relations
Citigate Sard Verbinnen                               718/403-2503
212/687-8080                                          jfisher@keyspanenergy.com
                                                      -------------------------
                                                      Carmen Fields
                                                      Director, Media/
                                                      Corporate Relations
                                                      781-466-5096
                                                      cfields@keyspanenergy.com
                                                      -------------------------

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