4 August 2026

National Grid plc / National Grid Electricity Transmission plc

Publication of a Supplementary Prospectus

The following supplementary prospectus has been approved by the Financial Conduct Authority and is available for viewing:

The Supplementary Prospectus dated 4 August 2026 (the "Supplementary Prospectus") supplementing the prospectus dated 19 August 2025 (as supplemented by the first supplement to the prospectus dated 23 January 2026 (together, the "Prospectus")) for the National Grid plc and National Grid Electricity Transmission plc Euro 20,000,000,000 Euro Medium Term Note Programme.

The Supplementary Prospectus should be read and construed in conjunction with the Prospectus.

To view the full Supplementary Prospectus, please paste the following URL into the address bar of your browser:

http://www.rns-pdf.londonstockexchange.com/rns/2538P_1-2026-8-4.pdf

A copy of the Supplementary Prospectus has been submitted to the National Storage Mechanism and will shortly be available to the public for inspection at https://data.fca.org.uk/#/nsm/nationalstoragemechanism.

For further information, please contact:

DISCLAIMER - INTENDED ADDRESSEES

Please note that the information contained in the Prospectus may be addressed to and/or targeted at persons who are residents of particular countries (specified in the Prospectus) only and is not intended for use and should not be relied upon by any person outside these countries and/or to whom the offer contained in the Prospectus is not addressed. Prior to relying on the information contained in the Prospectus you must ascertain from the Prospectus whether or not you are part of the intended addressees of the information contained therein.

Your right to access this service is conditional upon complying with the above requirement.