Transaction in Own Shares

National Grid PLC
20 December 2006



National Grid plc
20 December 2006

National Grid plc announces that on 19 December 2006 it purchased for
cancellation 90,000 of its ordinary shares at a price of 747.905 pence per share
from Deutsche Bank AG London Branch.

Following the purchase and upon the cancellation of these shares, the number of
ordinary shares in issue will be 2,718,936,688

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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