Transaction in Own Shares

National Grid PLC
21 September 2007

National Grid plc - Transaction in Own Shares

21 September 2007

National Grid plc announces that on 20 September 2007 it purchased for
cancellation 934,000 of its ordinary shares at a price of 776.1075 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
2,598,793,983 and the number of ordinary shares in Treasury will be 13,601,486.


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