Transaction in Own Shares

National Grid PLC
21 November 2007



National Grid plc - Transaction in Own Shares

21 November 2007


National Grid plc announces that on 20 November 2007 it purchased 989,404 of its
ordinary shares at a price of 785.4942 pence per share from Morgan Stanley
Securities Limited. The purchased shares will be held as Treasury shares.

Following the purchase of these shares, the number of ordinary shares with
voting rights in issue (excluding Treasury shares) will be 2,564,928,259 and the
number of ordinary shares in Treasury will be 16,985,257.





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