Lancaster Maclean clients have included the following: Acorn Addax Anadarko BG BHP Billiton BP group Burlington Resources Centrica CNR ENI group E.On group ExxonMobil First Oil Gaz de France Hess Intrepid IOC Murphy Nautical Nimir (now Knightsbridge) OPC Petro Summit Investments UK Premier Oil group RWE Shell group SOCO Talisman Total group Tullow group