Transaction in Own Shares

National Grid PLC
22 January 2007



National Grid plc

22 January 2007

National Grid plc announces that on 19 January 2007 it purchased for
cancellation 600,000 of its ordinary shares at a price of 734.70 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 2,714,626,373.


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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