19 January 2017

National Grid plc ("National Grid")

Transaction in Own Shares

National Grid announces that at 16:51:00 on 19 January 2017 it has purchased 700,000 of its Ordinary shares of 11^17/43p each on the London Stock Exchange from Barclays Capital Securities Limited ("Barclays") at a price of 935.2638p per share as part of its buy-back programme announced on 24 November 2016. National Grid intends to hold the purchased shares in treasury.

Following the purchase of these shares, National Grid holds 187,636,542 of its Ordinary shares in treasury and has 3,755,346,905 Ordinary shares in issue (excluding treasury shares).

In accordance with Article 5(1)(b) of the Market Abuse Regulation (EU) No 596/2014 details of the purchase of its own Ordinary shares by National Grid from Barclays are set out below:

This announcement will also be available on National Grid's website http://investors.nationalgrid.com/rns.aspx.  

Enquiries to:

D Whincup, Assistant Company Secretary, (0207 004 3209).