SIP Operation

National Grid PLC
10 July 2006


National Grid plc (NG)


Monday 10 July 2006
National Grid 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 41,949 NG. ordinary shares under
the scheme was confirmed by the Trustee last Friday, the shares having been
purchased in the market on 7 July 2006, at a price of 597 pence per share, on
behalf of some 2,750 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        21 Ordinary Shares            650,795 Ordinary Shares
Roger Urwin            21 Ordinary Shares            1,430,949 Ordinary Shares
                                                     281,977 B Shares- unchanged


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


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