Sark Well Central Oklahoma USA Update

5 November 2025

This announcement contains inside information for the purposes of Article 7 of the Market Abuse Regulation (EU) 596/2014 as it forms part of UK domestic law by virtue of the European Union (Withdrawal) Act 2018 ("MAR"), and is disclosed in accordance with the Company's obligations under Article 17 of MAR.

Union Jack Oil plc

("Union Jack" or the "Company")

Sark Well Central Oklahoma USA Update

Union Jack Oil plc (AIM: UJO, OTCQB: UJOGF), a UK and USA focused onshore hydrocarbon, production, development, exploration and investment company, announces that, further to the Company's announcement of 24 September 2025, the Company is providing an update on the Sark well ("Sark"), located in Central Oklahoma, USA. Union Jack holds a 53% interest in Sark.

Sark was drilled to a Total Depth of 5,391 feet and the Prue interval was highlighted on electric logs as hydrocarbon bearing following evaluation.

Temporary production facilities were installed and a 30-day test programme was undertaken. The production test of the Prue Sandstone failed to produce commercial hydrocarbons.

Post well analysis indicates the Sark well encountered a valid structural closure, however, the trap was subsequently breached.

David Bramhill, Executive Chairman of Union Jack, commented: "Following the drilling of four successful discoveries in Oklahoma to date, this is an unexpected and disappointing result. Our US interests, with income from Moccasin, the Andrews Field and Mineral Royalties, continue to be profitable and we look forward to continuing our Oklahoma drilling programme."

For further information, please contact:

Union Jack Oil plc [email protected]

David Bramhill

SP Angel Corporate Finance LLP +44 (0)20 3470 0470

Nominated Adviser and Joint Broker

Matthew Johnson

Richard Hail

Jen Clarke

Zeus +44 (0)20 3829 5000

Joint Broker

Antonio Bossi

Simon Johnson

George Duxberry

Gneiss Energy Limited + 44 (0)20 3983 9263

Financial Adviser

Jon Fitzpatrick

Paul Weidman

Harbour Access +1 (475) 477 9402

USA Investor Relations

Jonathan Paterson