SIP Operation

National Grid PLC
08 December 2005


National Grid plc (NG)

8 December 2005

NG SHARE INCENTIVE PLAN (the 'SIP')

(Notification of Directors' Interests, pursuant to Section 324(2) of the
Companies Act 1985)

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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 44,659 NG ordinary shares under
the scheme was confirmed by the Trustee yesterday, the shares having been
purchased in the market on 7 December 2005, at a price of 540.5 pence per share,
on behalf of some 2,700 participants.

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

Director               Shares purchased in SIP       Resulting total interest
Steven Holliday        23 Ordinary Shares            559,403 Ordinary Shares
Roger Urwin            23 Ordinary Shares            1,501,131 Ordinary Shares
                                                     281,977 B Shares- unchanged


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


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