Transaction in Own Shares

National Grid PLC
21 February 2007


National Grid plc announces that on 20 February 2007 it purchased for
cancellation 700,000 of its ordinary shares at a price of 782.8311 pence per
share.

Following the purchase and upon the cancellation of these shares, the number of
ordinary shares with voting rights in issue will be 2,710,713,495.
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