SIP Operation

National Grid PLC
12 December 2007


National Grid plc ('NG')



12th December 2007



Notification of Directors' Interests



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NG SHARE INCENTIVE PLAN (the 'SIP')



Under the SIP scheme, operated through Towers Perrin Share Plan Services Limited
as Trustee, employees may acquire NG ordinary shares by regular monthly
contributions.  The current monthly purchase of 26,904 NG ordinary shares under
the scheme was confirmed by the Trustee yesterday, the shares having been
purchased in the market on Friday 7th December, at a price of 835 pence per
share, on behalf of some 2,500 participants.



The following executive Directors of NG are beneficiaries of the number of
shares purchased on their behalf:


Director                       Shares purchased in SIP
Mark Fairbairn                 15 Ordinary Shares
Steven Holliday                15 Ordinary Shares





The Directors total interests after these events are:


Director                             Resulting total interest
Mark Fairbairn                       357,187 Ordinary Shares
Steven Holliday                      794,316 Ordinary Shares



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Contact: D C Forward, Assistant Secretary- (0207 004 3226)


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