Transaction in Own Shares

National Grid PLC
13 March 2007

National Grid plc announces that on 12 March 2007 it purchased for cancellation
700,000 of its ordinary shares at a price of 770.1387 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 2,704,682,769.
--------------------------------------------------------------------------------


                      This information is provided by RNS
            The company news service from the London Stock Exchange