Transaction in Own Shares

National Grid PLC
10 January 2007



National Grid plc
10 January 2007

National Grid plc announces that on 9 January 2007 it purchased for cancellation
500,000 of its ordinary shares at a price of 724.79 pence per share from
Deutsche Bank AG London Branch.

Following the purchase and upon the cancellation of these shares, the number of
ordinary shares with voting rights in issue will be 2,716,464,569.


CONTACT DETAILS

Investors
David Rees         [phone]           [phone](m)
Richard Smith      [phone]           [phone](m)
James Waite        [phone]           [phone](m)

Media
Clive Hawkins      [phone]           [phone](m)


END




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