Total Voting Rights

11th May 2010

National Grid plc (National Grid)

Voting Rights and Capital update

National Grid has been notified that, yesterday, Monday 10th May 2010,

68,858 shares held in Treasury were transferred to share scheme participants. Following this change, National Grid plc's registered capital from 10 May 2010 consists of 2,617,190,095 ordinary shares, of which 141,122,513 have been purchased in the market and registered as Treasury Shares; leaving a balance of 2,476,067,582 shares with voting rights.

The figure of 2,476,067,582 may be used by shareholders as the denominator for the calculations by which they will determine if they are required to notify their interest in, or a change to their interest in, National Grid plc under the FSA's Disclosure and Transparency Rules.

Contact: D C Forward,

Assistant Secretary

0207 004 3226