Holding(s) in Company

11th June 2013

National Grid plc (National Grid)

Notification of Major Interest in National Grid Ordinary Shares

National Grid received late yesterday a notification on Form TR-1 from The Capital Group Companies, Inc. that its total interest in National Grid voting ordinary shares was, at 7 June 2013, at 10.974%, a total of 402,496,950 shares (previously notified at 3 April 2013, at 11.02%, a total of 404,063,006 shares).

This notice is given in fulfilment of National Grid's obligations under the Disclosure and Transparency Rules.

D C Forward

Assistant Secretary

0207 004 3226