SIP Operation

National Grid PLC
11 March 2008



National Grid plc ('NG')


11th March 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 31,587 NG ordinary shares under
the scheme was confirmed by the Trustee late yesterday, the shares having been
purchased in the market on Friday 7th March, at a price of 716 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                 17 Ordinary Shares
Steven Holliday                17 Ordinary Shares



The Directors total interests after these events are:


Director                             Resulting total interest
Mark Fairbairn                       311,089 Ordinary Shares
Steven Holliday                      679,247 Ordinary Shares



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


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