April 11, 2006

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

                            SCHEDULE 14A INFORMATION
                                 (Rule 14a-101)

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

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Filed by a Party other than the Registrant  [ ]

Check the appropriate box:
[ ]     Preliminary Proxy Statement
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        Rule 14a-6(e)(2))
[ ]     Definitive Proxy Statement
[ ]     Definitive Additional Materials
[X]     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)

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     to Exchange  Act Rule 0-11 (set forth the amount on which the filing fee is
     calculated and state how it was determined):
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The following letter from Robert B. Catell, Chairman and Chief Executive Officer
is being  distributed  to all KeySpan  shareholders  as part of the 2005 KeySpan
Annual Report. The Annual Report is being mailed on or about April 11, 2006.


Dear Fellow Shareholder,


For  KeySpan,  2005 was a year  defined  by  strong  operational  and  financial
performance in an increasingly  complex  environment.  It was this performance -
and indeed our  sustained  performance  over the last eight years - that set the
stage for us to take a bold,  exciting  and  decisive  step  into the  future on
February 27, 2006.

On that date,  KeySpan  announced a definitive  agreement  with National Grid in
which National Grid will acquire all the outstanding  shares of KeySpan for $7.3
billion  in cash or $42 per  share.  While both  companies'  boards  unanimously
approved the agreement,  shareholder and certain other regulatory  approvals are
necessary to achieve a targeted  completion  date of early 2007.  Upon approval,
KeySpan  will  become  a  wholly  owned   subsidiary  of  National  Grid.  As  a
shareholder,  you will be receiving materials in the near future concerning this
transaction.

At a time when energy costs and industry  consolidation  are defining the future
of our industry, this agreement provides a premium return on your investment. It
provides  the  platform  that will  create a  stronger  company  that can better
compete  and win in a  progressive,  deregulated  marketplace  - one where size,
scale  and  balance  are  important  strategic  differentiators  for  long-term,
sustainable  growth.  Upon  approval,  KeySpan will join with  National  Grid to
establish the third largest energy delivery company in terms of customers in the
United States.

As part of this larger company, we'll have access to greater resources to better
tackle the tough  issues - like  high-priced,  volatile  energy  markets and the
ability to meet customers'  demand for energy through enhanced  supply,  natural
gas pipelines and  infrastructure.  And because National Grid's U.S. business is
focused on the  Northeast,  where our combined  service areas are  contiguous in
many  places,  there are many  opportunities  to achieve  economies of scale and
reduce costs for customers.

In short,  KeySpan will become an important  part of one of the most  efficient,
reliable and growth-focused energy delivery companies in the world.

BUILDING THE PLATFORM

KeySpan's  excellent financial  performance,  core expertise in gas and electric
operations, and our strong record in customer and community service all played a
large role in why National Grid found KeySpan so valuable and attractive. And it
provides the foundation for what promises to be a fruitful  relationship for the
new, combined company and its customers and shareholders.


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In 2005,  we  delivered  solid core  earnings  per share of $2.37,  in line with
analysts' estimates and an increase of 5 percent as compared to 2004. We reduced
our  debt-to-capitalization  ratio  from  more than 53  percent  to less than 51
percent,  further  improving  our balance  sheet.  And in  December,  your board
approved  an annual  dividend  increase  of four cents to $1.86 per  share,  the
second consecutive year we were able to raise the dividend. KeySpan shareholders
will continue to receive  quarterly  dividend  payments until  completion of the
transaction.

Despite  the  challenge  of higher  gas  commodity  prices,  which  resulted  in
increased  uncollectible  accounts and less usage per  customer,  KeySpan's  gas
business  completed 46,000 gas  installations in 2005, adding almost $50 million
in new gross profit  margin.  Net revenues were higher than 2004 by $48 million.
Overall,  KeySpan realized  another year of organic growth,  which helped offset
the impact of higher costs.

The electric business also performed exceptionally.  The Ravenswood facility and
all of the Long Island  generating units were close to 100 percent available and
operating at top  performance  during the very hot summer.  This  combination of
availability  and efficiency  helped earn $342 million in operating  income,  18
percent higher than 2004.

And our new, enhanced  agreement with the Long Island Power Authority (LIPA) was
a case study in managing  complexity.  With no  archetype  to follow,  we had to
produce our own working,  flexible model for this unique relationship - one that
would provide benefit for shareholders,  employees and Long Island consumers. We
worked in  partnership  with LIPA to  diligently  achieve these  objectives  and
create  certainty in our Long Island electric  operations  through 2013. Now, we
look forward to bringing  the  benefits of our combined  company to LIPA and all
its customers.

We bring these  strengths  - and more - to the table.  Combining  with  National
Grid, of course, also gives us a myriad of benefits that we wouldn't have on our
own. It gives us the  opportunity to lower risk and compete as a stronger player
in the midst of a changing marketplace.  And it allows us to drive growth to new
heights,  as part of a bigger  company  that will  have the scale and  resources
necessary to enhance customer service and grow in today's complex environment.

AN IDEAL COMBINATION

Beyond the numbers, it's also an excellent fit for both companies. Both National
Grid and KeySpan are dedicated to supply diversity and delivering  energy in the
most  efficient,   cost-effective  way  to  customers.   Both  look  to  achieve
outstanding operational performance in the most economical manner possible. Both
have a substantial  commitment to the local  communities  we serve,  the natural
environment  we operate in, and the  principles  of sound  fiscal and  corporate
accountability.   And  both  boast  a  core  of  excellent   employees  who  are
technological leaders.


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AN EXCITING FUTURE

Clearly,  this is a bold step for KeySpan. But one that I feel is both necessary
and evolutionary.  And while employees may naturally feel some uncertainty, both
companies  are committed to achieve any staff  reductions  sensitively - through
attrition and voluntary  programs.  Overall, I see much upside potential for our
excellent  employees to develop their talents and expand their  opportunities as
part of a global company.

Upon completion of the transaction, I will become executive chairman of National
Grid's U.S.A.  operation for two years. I will also serve as deputy  chairman on
National  Grid's  14-member  board in the  United  Kingdom,  where one member of
KeySpan's  current  board will join me,  ensuring a strong role in the  combined
company. I especially look forward to working with Mike Jesanis,  who will serve
as president  and chief  executive  officer of the combined  company,  and Steve
Holliday,  chief executive designate of National Grid plc. I have come to better
know these two talented and experienced men over the last several months - and I
assure you we share a common philosophy and vision.

I've enjoyed a highly satisfying 48 years in this business;  the last eight have
been especially fulfilling.  My thanks to our loyal shareholders who've invested
their hard-earned dollars with us, and to our employees, who've made our success
possible.  I also  want  to  thank  KeySpan's  board  of  directors;  they  were
instrumental  in making KeySpan the company we are today - and making us part of
the company we will be tomorrow.

As I conclude  this letter,  I'm  confident  and excited  about the future.  The
KeySpan Corporation is poised to build on our successful history as a vital part
of a larger, stronger company that can lay claim to the title we've relentlessly
pursued since KeySpan was formed: the premier energy company in the Northeast.


/s/Robert B. Catell
Robert B. Catell
Chairman and Chief
Chairman and Chief Executive Officer

March 21, 2006


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

KeySpan intends to file with the Securities and Exchange  Commission (the "SEC")
a proxy  statement and other relevant  documents in connection with the proposed
acquisition  of KeySpan by National  Grid.  Investors  and  security  holders of
KeySpan are advised to read the proxy  statement  and other  relevant  documents
when they become available, as they will contain important information about the
transaction.  Investors and security holders may obtain a free copy of the proxy
statement  and other  documents  filed by KeySpan with the SEC, when they become
available, at the SEC'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 security  holders in connection with the proposed  acquisition.
Information   concerning  the  interests  of  KeySpan's   participants   in  the
solicitation  is set forth in KeySpan's  most recent proxy  statement and Annual
Report on Form 10-K (filed with the SEC on March 30, 2005 and February 28, 2006,
respectively)  and will be set  forth in the  proxy  statement  relating  to the
acquisition when it becomes available.








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