SIP Operation

National Grid PLC
08 May 2008

National Grid plc ('NG')



8th May 2008



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 33,514 NG ordinary shares under
the scheme was confirmed by the Trustee yesterday, the shares having been
purchased in the market on Wednesday 7th May, at a price of 703 pence per share,
on behalf of some 2,500 participants.



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


Director                       Shares purchased in SIP
Mark Fairbairn                 18 Ordinary Shares
Steven Holliday                18 Ordinary Shares





The Directors total interests after these events are:


Director                             Resulting total interest
Mark Fairbairn                       311,124 Ordinary Shares
Steven Holliday                      679,282 Ordinary Shares



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


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