Holding(s) in Company

5 August 2015

National Grid plc (National Grid)

Notification of Major Interest in National Grid Ordinary Shares

National Grid received on 5 August 2015 a notification by way of Form TR-1 from Competrol International Investments Limited ("Competrol"), regarding total return equity swaps with an expiration date of 21 July 2016.

The notification confirmed that following the announcement of National Grid's total voting rights on 3 August 2015, Competrol's total interest in National Grid ordinary shares represented 4.01% of the total issued share capital, a total of 149,414,285 shares (previously notified to National Grid on 18 July 2014, at 3.99%, a total of 149,414,285 shares).

This notice is in compliance with National Grid's obligations under the Disclosure and Transparency Rules.

David Whincup

Company Secretarial Assistant

0207 004 3209