Transaction in Own Shares

National Grid PLC
18 February 2008

National Grid plc - Transaction in Own Shares

18 February 2008

National Grid plc announces that on 15 February 2008 it purchased 312,525 of its
ordinary shares at a price of 779.7563 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 2,530,289,614 and the
number of ordinary shares in Treasury will be 51,623,902.



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