Transaction in Own Shares

National Grid PLC
12 March 2007

National Grid plc announces that on 09 March 2007 it purchased for cancellation
500,000 of its ordinary shares at a price of 770.9210 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 2,705,382,769.
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