July 12, 2006

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                            SCHEDULE 14A INFORMATION

                  Proxy Statement Pursuant to Section 14(a) of
            the Securities and Exchange Act of 1934 (Amendment No. )

Filed by the Registrant [X]
Filed by a Party other than the Registrant [ ]

Check the appropriate box:
[ ]     Preliminary Proxy Statement
[ ]     Confidential, For Use of the Commission Only (as permitted by
        Rule 14a-6(e)(2))
[ ]     Definitive Proxy Statement
[X]     Definitive Additional Materials
[ ]     Soliciting Material Pursuant to Section 240.14a-12

                              KeySpan Corporation
                              -------------------
                (Name of Registrant as Specified in Its Charter)

                                     (N/A)
                                     -----
    (Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

Payment of Filing Fee (Check the appropriate box):
[X]     No fee required.
[ ]     Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.

(1)  Title of each class of securities to which transaction applies:
     N/A______________________________________________________________
(2)  Aggregate number of securities to which transaction applies:
     N/A______________________________________________________________
(3)  Per unit price or other underlying value of transaction  computed  pursuant
     to Exchange  Act Rule 0-11 (set forth the amount on which the filing fee is
     calculated and state how it was determined):
     N/A______________________________________________________________
(4)  Proposed maximum aggregate value of transaction:
     N/A______________________________________________________________
(5)  Total fee paid:
     N/A______________________________________________________________

[ ]     Fee paid previously with preliminary materials.

[ ]     Check box if any part of the fee is offset as provided by Exchange Act
        Rule  0-11(a)(2)  and identify the filing for which the offsetting fee
        was  paid  previously.   Identify  the  previous  filing  registration
        statement number, or the Form or Schedule and date of its filing.




(1)  Amount Previously Paid:
     N/A______________________________________________________________
(2)  Form, Schedule or Registration Statement No.:
     N/A______________________________________________________________
(3)  Filing Party:
     N/A______________________________________________________________
(4)  Date Filed:
     N/A______________________________________________________________

















                                       2





Attached  is a copy of a press  release  issued  by  National  Grid and  KeySpan
Corporation.


nationalgrid                                                             KEYSPAN

              NATIONAL GRID ACQUISITION OF KEYSPAN CLEARS REVIEW OF
            THE COMMITTEE ON FOREIGN INVESTMENT IN THE UNITED STATES

Westborough,  MA and Brooklyn,  NY (July 12, 2006) - National  Grid (LSE:  NG.L,
NYSE: NGG) and KeySpan  Corporation  (NYSE:  KSE) today announced they have been
notified  that the  Committee  on Foreign  Investment  in the United  States has
completed  review of National  Grid's  proposed  acquisition  of KeySpan and has
determined that there are no issues of national  security  sufficient to warrant
an investigation of this transaction.

The  Committee  on Foreign  Investment  in the United  States is an  interagency
committee chaired by the Department of the Treasury authorized to review foreign
acquisitions of U.S. companies.

Remaining  approvals for the acquisition  include  authorization  by the Federal
Energy Regulatory  Commission and by the New York Public Service  Commission and
the New Hampshire Public Utilities Commission.

On February  27, 2006,  National  Grid and KeySpan  announced  an agreement  for
National  Grid to  acquire  KeySpan,  which will  materially  expand the size of
National Grid's US operations and create the  third-largest gas delivery utility
in the United States.  The acquisition is a natural extension of National Grid's
business and will result in electricity and gas businesses  serving nearly eight
million customers in the New York State and New England regions.

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  will be  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 year,  National Grid announced that it
will  acquire the Rhode  Island gas  distribution  business  of  Southern  Union
Company.

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.   For   more
information, visit National Grid's web site at www.nationalgrid.com.


                                       3





National Grid/KeySpan (cont.)
Pg 2.



About KeySpan:
- --------------
A member of the Standard & Poor's 500 Index,  KeySpan Corporation  (NYSE:KSE) is
the fifth  largest  distributor  of  natural  gas in the  United  States and the
largest  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 www.keyspanenergy.com.


Media Contacts:

National Grid
Alberto Bianchetti
315-428-6932

KeySpan
718-403-2503
24-hour pager: 516-824-1241






                                       4






Additional Information and Where to Find It
- -------------------------------------------

In connection with the proposed merger, the Company has filed a definitive proxy
statement with the Securities and Exchange Commission.  BEFORE MAKING ANY VOTING
OR  INVESTMENT  DECISION,  THE  COMPANY  STOCKHOLDERS  ARE  URGED  TO  READ  THE
DEFINITIVE PROXY STATEMENT BECAUSE IT CONTAINS  IMPORTANT  INFORMATION ABOUT THE
PROPOSED MERGER. The definitive proxy statement is also available free of charge
at  the  Securities  and  Exchange   Commission's  website,   www.sec.gov,   and
stockholders  of the  Company are also able to obtain  additional  copies of the
definitive proxy statement free of charge by directing their requests to KeySpan
Corporation One MetroTech Center, Brooklyn, New York 1120-3850.


The  Company  and its  directors  and  executive  officers  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 the Company's
participants in the  solicitation is set forth in the Company's proxy statements
and Annual  Reports  on Form 10-K,  previously  filed  with the  Securities  and
Exchange  Commission,  and in the  definitive  proxy  statement  relating to the
merger.






                                       5