Exhibit 10.1







March 24, 2006

Mr. Gerald Luterman
One Metrotech Center
Brooklyn, N.Y.11201


                        Senior Executive Change of Control Severance Plan
                        -------------------------------------------------

Dear Gerry:


     Reference  is  made  to the  KeySpan  Corporation  (the  "Company")  Senior
Executive  Change of Control  Severance  Plan (the "Plan") and the Agreement and
Plan of Merger between the Company and National Grid, PLC and National Grid US8,
Inc. dated February 25, 2006 (the "Merger  Agreement").  Capitalized  terms used
herein  without  definition  have the meanings  assigned to such terms under the
Plan.

     The KeySpan Board of Directors has  designated  you as a Participant  under
the Plan with a multiple of Three (3X).  Pursuant to the terms of the Plan,  you
may be entitled to receive  certain  Separation  Benefits in the event that your
employment is terminated  without Cause or for Good Reason during the Protection
Period.  The amount of your  Separation  Benefits is  determined by reference to
your Multiple of 3 under the Plan,  with the term  "Multiple"  defined under the
Plan as the  lesser of (i) the  number  set forth  opposite  your name under the
heading  "Benefit Level" on Schedule I to the Plan (i.e., the number 3) and (ii)
the  number  of  years  and  fractions  thereof  remaining,  as of your  Date of
Termination,  until you reach your  mandatory  retirement age (if any) under the
applicable Company policy.

     In the event that the  "Merger"  (as  defined in the Merger  Agreement)  is
consummated  on or prior to March 31,  2008 and your  employment  is  terminated
pursuant to a notice of termination or notice of resignation for Good Reason, as
such term is defined in the Plan,  upon such  consummation  date pursuant to the
provisions of this Letter Agreement,  the Company will provide you with benefits
equivalent  to the  Separation  Benefits  under the Plan with a  Multiple  of 3X
without  regard to your age at the your  Date of  Termination  or any  mandatory
retirement  age (if any)  under the  applicable  Company  policy,  offset by the
benefit  you  actually  receive  under the  Plan.  The (i)  aggregate  amount of
benefits under this Letter Agreement and (ii) the Separation  Benefits under the
Plan provided to you shall not exceed a Multiple of 3X.

     In the event  that the Merger is not  consummated  on or prior to March 31,
2008, this Letter  Agreement shall be void ab initio and your rights (if any) to
receive  Separation  Benefits  shall be determined  pursuant to the terms of the
Plan without regard to this Letter Agreement.





     This Letter  Agreement does not  constitute a contract of  employment,  nor
does it  impose  on you or the  Company  any  obligation  for you to  remain  an
employee  or change  the status of your  employment  or the  Company's  policies
regarding  termination  of  employment.  Except as  expressly  set forth in this
Letter Agreement,  your rights to receive Separation Benefits under the Plan are
subject to the terms and conditions set forth in the Plan.




                                         Very truly yours,




                                         KEYSPAN CORPORATION



                                         By:/s/Robert B. Catell
                                            -------------------
                                                Robert B. Catell
                                            Chairman and Chief Executive Officer



Agreed and Accepted:

/s/Gerald Luterman
- --------------------
Gerald Luterman





                                       2