Transaction in Own Shares

National Grid PLC
21 May 2007


National Grid plc

21 May 2007

National Grid plc announces that on 18 May 2007 it purchased for cancellation
2,200,000 of its ordinary shares at a price of 763.876 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 2,702,650,553.


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