Exhibit 99.1
SUMMARY
FORM 6-K
SECURITIES AND EXCHANGE COMMISSION
Washington D.C. 20549
Report of Foreign Issuer
Pursuant to Rule 13a – 16 or 15d – 16
of The Securities Exchange Act of 1934
Announcements sent to the London Stock Exchange
National Grid plc, 1-3 Strand, London, WC2N 5EH, United Kingdom
Update — Routine announcements in the period to 3 May 2018
| 1 May 2018 | Total Voting Rights | |
| 10 April 2018 | Director/PDMR Shareholding |
Note: During the period a ‘same day’ Form 6-K was issued in respect of the following National Grid plc announcements:
| 12 April 18: | National Grid Pre-Close update to 2017/18 Technical Guidance | |
| 13 April 18: | Appointment of Joint Corporate Broker | |
| 19 April 18: | Board Change | |
| 1 May 18: | Agreement for the potential sale of remaining 25% interest in Cadent Gas | |