Oil and gas explorer Gulf Keystone on Monday announced that its Finance Director, Ewen Ainsowrth, is planning to leave the company with almost immediate effect.The group said the search for his replacement is underway and potential candidates have been identified. In the meantime, Financial Controller Mary Hood will takeover the role as acting Chief Financial Officer. Chairman Simon Murray said: "Over his six years with Gulf Keystone Ewen has played a key role in the company's growth and we thank him for his dedication. Now, with our main market move and recent $250m bond financing behind us this is a good time to make a transition."The share price had fallen 1.36% to 80.39p by 08:43.NR