Transaction in Own Shares

National Grid PLC
17 October 2007

National Grid plc - Transaction in Own Shares

17 October 2007

National Grid plc announces that on 16 October 2007 it purchased for
cancellation 830,000 of its ordinary shares at a price of 780.7129 pence per
share from Morgan Stanley Securities Limited.

Following the purchase and upon cancellation of these shares, the number of
ordinary shares with voting rights in issue (excluding Treasury shares) will be
2,588,791,891 and the number of ordinary shares in Treasury will be 13,133,370.



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