Hague and London Oil Regulatory News (HNL)

Embargoed for Release: 0700 on 23 July 2013

Wessex Exploration PLC

("Wessex" or "the Company")

Completion of GM-ES-4 Exploration Well

Further to the release on 8th May 2013, Wessex Exploration PLC (AIM:WSX) announces the conclusion of drilling activities on the GM-ES-4 well in French Guiana.

The well penetrated the primary and secondary reservoir objectives before drilling operations were concluded at a total depth of 6,292m. The results of the wireline logging programme has confirmed the presence of reservoir, however no evidence of hydrocarbons is seen from the drilling or wireline log data. The well is now being plugged and abandoned.

The Stena ICEMax will now drill the GM-ES-5 exploration well, which will be located on the Cingulata fan in which the Zaedyus discovery was made in 2011. The well is designed to explore deeper targets within the Cingulata fan complex as well as testing the potential downdip extension of the GM-ES-1 discovery.

GM-ES-5 is the last in a four well exploration drilling campaign that commenced in mid 2012 to follow up the Zaedyus oil discovery made in 2011.

Wessex owns a net 1.25 per cent interest in the offshore exploration licence 'Guyane Maritime' through its holding of 50 per cent of Northpet Investment Limited. Wessex is in partnership with Shell (Operator, holding 45 per cent), Tullow (27.5 per cent), Total (25 per cent) and Northern Petroleum Plc (also holding 1.25 per cent through owning the remaining 50 per cent interest in Northpet Investment Limited).

In accordance with the AIM Rules - Guidance for Mining and Oil & Gas Companies, the information contained in this announcement has been reviewed and signed off by the Chairman of Wessex, Dr Malcolm Butler PhD, BSc, CGeol, FGS who has over 40 years' experience as a petroleum geologist. He has compiled, read and approved the technical disclosure in this regulatory announcement. The technical disclosure in this announcement complies with the SPE/WPC standard.

Malcolm Butler, Chairman of Wessex Exploration PLC stated:

"Although the GM-ES-4 well did not encounter hydrocarbons, the data from this well will now be integrated with that from the previous wells drilled by the group to assist in the interpretation of the new 'Central Slope' 4,300 square kilometres 3D seismic volume. The additional information will help the partnership understand and minimise the risks of new leads and prospects being developed within in the Guyane Maritime permit. I now look forward to the drilling of the GM-ES-5 well and the opportunity that it presents the Company and Shareholders."

For further information please contact:

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Notes to Editors on WSX:

Guyane

Wessex holds a net 1.25% interest in the Exclusive Exploration Licence (EEL) covering an approximate 24,100 sq.km offshore area of Guyane (a French prefecture previously known as French Guiana). The EEL interest is held via a 50/50 joint venture between Wessex and Northern Petroleum Plc, using Northpet Investments Limited as the holding company with a total interest of 2.5%. The other partners in Guyane are Shell (45% and operator), Tullow (27.5%) and Total (25%).

Juan de Nova

Wessex holds a 70% interest in the Juan de Nova Est Permit, covering 9,010 sq. km in water depths ranging from 200m to 3,000m, to the east of Juan de Nova Island in the Mozambique Channel. Wessex has been designated as operator, subject to the approval of the French authorities. Global Petroleum Limited (AIM: GBP, ASX: GBP) has a 30% interest.

Southern United Kingdom

Wessex holds three licences in southern United Kingdom - PEDL 238: 50%; PEDL 239: 25%; P1928: 35% - alongside its partner and operator, NWE Mirrabooka (UK) Pty. Ltd (a fully owned subsidiary of ASX listed Norwest Energy NL).

Saharawi Arab Democratic Republic (SADR, Western Sahara)

Wessex holds three blocks - Bojador (39,983 sq.km), Guelta (15,760 sq.km) and Imlili (16,955 sq.km) - under Assurance Agreements which cause Production Sharing Contracts to come into effect once the SADR government is able to take control of the territory. Wessex is the designated operator and holds a 50% interest; Tower Resources (AIM: TRP) has the other 50% interest.