The information contained within this announcement is deemed by the Company to constitute inside information under the Market Abuse Regulation (EU) No. 596/2014, as it forms part of UK domestic law by virtue of the European Union (Withdrawal) Act 2018. Upon publication of this announcement, this information is now considered to be in the public domain.

UK Oil & Gas PLC

("UKOG" or the "Company")

Significant Horndean Reserves Increase

UK Oil & Gas PLC (London AIM: UKOG) is pleased to announce that, further to the Company's RNS of 10 February 2025, a new Reserves Report ("Report"), carried out for the Horndean field operator (Star Energy Group plc), has assessed that the field's remaining reserves have increased by up to 62% compared to the same period one year ago. UKOG's wholly owned subsidiary UKOG GB holds a 10% non-operated interest in Horndean.

The Report's assessed gross reserves as of 31^st December 2024 and the reserve increase versus 31^st December 2023, are summarised below:

· A 62% increase in proven (1P) reserves to 1.5 million barrels ("mmbbl", UKOG net 0.150 mmbbl)

· A 55% increase in proven plus probable (2P) reserves to 1.65 mmbbl (UKOG net 0.165 mmbbl)

· A 53% increase in proven plus probable plus possible (3P) reserves to 1.82 mmbbl (UKOG net 0.182 mmbbl)

· The assessed 2P reserve increase equates to 12 times the 2024 field production of 49,402 bbl.

The increase in reserves is a direct result of increased field performance via the combination of recent well workovers and the prior installation of new electric pumps in mid-2023 (see RNS of 28^th June 2024).

The Report was prepared in accordance with the Petroleum Resources Management System approved by the Society of Petroleum Engineers.

Horndean reserves and contingent resources as of 31^st December 2024 are summarised in tables 1 and 2 below:

Table 1: Horndean Reserves as of 31/12/2024

Horndean	Full Field (100%)*			UKOG Net (10%)
PRMS Reserves Category	1P	2P	3P	1P	2P	3P
Recoverable oil (mmbbl)	1.50	1.65	1.82	0.15	0.17	0.18

Table 2: Horndean Contingent Resources as of 31/12/2024

Horndean	Full Field (100%)*			UKOG Net (10%)
PRMS Contingent Resource Category	1C	2C	3C	1C	2C	3C
Recoverable oil (mmbbl)	0.18	0.74	1.23	0.02	0.07	0.12

Note:* As assessed for the operator Star Energy by DeGolyer & MacNaughton

Stephen Sanderson UKOG's Chief Executive commented:

"We are delighted that the Horndean field's materially increased performance has now been fully reflected in an equally material increase in assessed reserves. The resultant increased asset value, even at current Brent prices, is most welcome."

Qualified Person's Statement

Matt Cartwright, UKOG's Commercial Director, who has 40 years of relevant experience in the global oil industry, has approved the information contained in this announcement. Mr Cartwright is a Chartered Engineer and member of the Society of Petroleum Engineers.

For further information, please contact:

UK Oil & Gas Plc

Stephen Sanderson / Kris Bone Tel: 01483 941493

Zeus (Nominated Adviser and Broker)

James Joyce / James Bavister / Andrew de Andrade Tel: 0203 829 5000

CMC Markets (Joint Broker)

Douglas Crippen Tel: 0203 003 8632

Communications

Brian Alexander Tel: 01483 941493

Glossary

1C		the low case estimate of Contingent Resources. There is estimated to be a 90% probability that the quantities actually recovered could equal or exceed this estimate, i.e., P90 case
2C		the mid-case or average estimate of Contingent Resources. There is estimated to be a 50% probability that the quantities actually recovered could equal or exceed this estimate, i.e., P50 case
3C		the high case estimate of Contingent Resources. There is estimated to be a 10% probability that the quantities actually recovered could equal or exceed this estimate, i.e., P10 case
	1P	The low case or proven estimate of Reserves. There is estimated to be a 90% probability that the quantities actually recovered could equal or exceed this estimate, i.e., P90 case
	2P	The mid-case or proven plus probable estimate of Reserves. There is estimated to be a 50% probability that the quantities actually recovered could equal or exceed this estimate, i.e., P50 case
	3P	The high case or proven plus probable plus possible estimate of Reserves. There is estimated to be a 10% probability that the quantities actually recovered could equal or exceed this estimate, i.e., P10 case
	bbl	Barrel of oil
Contingent Resources		those quantities of petroleum estimated, as of a given date, to be potentially recoverable from known accumulations, but the applied project(s) are not yet considered mature enough for commercial development due to one or more contingencies. Contingent Resources are further categorised in accordance with the level of certainty associated with the estimates and may be sub-classified based on project maturity and/or characterised by their economic status
	Reserves Report	A Petroleum Resources report prepared by an independent person(s), providing an estimated range of remaining recoverable resources and their potential monetary valuation in accordance with the relevant reporting standard (in this case the 2018 Society of Petroleum Engineers' PRMS). This Report has not been prepared under the AIM rules for oil & gas companies.
	Reserves	Those quantities of petroleum anticipated to be commercially recoverable by application of development projects to known accumulations from a given date forward under defined conditions. Reserves must satisfy four criteria: discovered, recoverable, commercial and remaining (as of the evaluation's effective date) based on the development project(s) applied. Reserves are further categorised in accordance with the level of certainty associated with the estimates and may be sub-classified based on project maturity and/or characterised by development and production status.
	mmbbl	Million barrels of oil