Transaction in Own Shares

National Grid PLC
17 December 2007


National Grid plc - Transaction in Own Shares


17 December 2007


National Grid plc announces that on 14 December 2007 it purchased 358,144 of its
ordinary shares at a price of 835.0817 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 2,553,052,421 and the
number of ordinary shares in Treasury will be 28,861,095.

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