EASTERN POWER NETWORKS PLC, LONDON POWER NETWORKS PLC, SOUTH EASTERN POWER NETWORKS PLC

PUBLICATION OF SUPPLEMENTARY PROSPECTUS

The following supplement to a prospectus (the "Supplement") has been approved by the Financial Conduct Authority and is available for viewing:

Supplement dated 6 March 2026 relating to the £10,000,000,000 Euro Medium Term Note Programme of each of Eastern Power Networks plc, London Power Networks plc and South Eastern Power Networks plc.

The Supplement should be read and construed in conjunction with the Offering Circular dated 30 July 2025 relating to the above programme.

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

http://www.rns-pdf.londonstockexchange.com/rns/7038V_1-2026-3-6.pdf

A copy of the Supplement has also been submitted to the National Storage Mechanism and will shortly be made available for inspection at:

https://data.fca.org.uk/#/nsm/nationalstoragemechanism.

For further information, please contact:

Andrew Kluth

Head of Treasury,

UK Power Networks

2nd Floor Newington House

237 Southwark Bridge Road

London SE1 6NP

Email: [email protected]

DISCLAIMER - INTENDED ADDRESSEES

Please note that the information contained in the Supplement and the Offering Circular may be addressed to and/or targeted at persons who are residents of particular countries (specified in the Offering Circular) 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 Offering Circular is not addressed. Prior to relying on the information contained in the Offering Circular you must ascertain from the Offering Circular 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.  

Neither this announcement nor the Supplement constitutes an offer of the Notes described in the Offering Circular for sale in the United States. This is not for distribution in the United States. The Notes have not been, and will not be, registered under the United States Securities Act of 1933, as amended (the "Securities Act") and are subject to U.S. tax law requirements. Subject to certain exceptions, Notes may not be offered, sold or delivered, directly or indirectly, in the United States or to, or for the account or benefit of U.S. persons, as such terms are defined in Regulation S under the Securities Act. There will be no public offering of the Notes in the United States.