The company said Sir Bill will move up to become non-executive chairman from July 1, when the current legal and commercial director Simon Thomson will become chief executive.
Chairman Norman Murray is standing down after 12 years on the board to focus on his work with Petrofac, the oil and gas services giant. Phil Tracy and Malcolm Thoms, engineering and operations specialists who have played a key role in the growth of the company, will also depart.
The company is making the changes during a period of uncertainty for the business.
Directors have spent 10 months seeking official approval for a multi-billion-pound deal to sell the bulk of its interests in India to Vedanta Resources. Yesterday the Indian Government decided to keep Cairn hanging on for a decision for at least another week.
Cairn’s hunt for oil and gas off Greenland has been disrupted by campaigners.
However, a spokesperson for Cairn Energy said the changes had been under careful consideration by the board for some time.
“We believe now is the right time for those changes and that they are the right way forward in particular as it provides clarity as Cairn looks to pursue future growth opportunities.”
The spokesperson said the move was unrelated to other issues.
The company canvassed major investors about Sir Bill’s move into the chairman’s role. Corporate governance activists are not keen on chief executives stepping into a chairman’s shoes, fearing they might be hard for their replacement to challenge.
Former Scotland rugby international Sir Bill is believed to have been preparing to move into a less hands-on role for some time. After making a series of huge discoveries in India’s Rajasthan state since 2004, Cairn has seen its capitalisation soar from £560 million to around £5.7 billion. Sir Bill’s responsibilities have increased from those associated with running a niche exploration firm to include overseeing the development of complex production facilities while conducting challenging dealings with Indian officialdom.
Sir Bill will retain overall responsibility for the proposed sale of 40% of Cairn India to Vedanta Resources for $6.6bn (£4bn).
“We don’t believe the changes will prejudice the Vedanta transaction not least because Sir Bill, as well as being chairman of Cairn Energy, will remain chairman of Cairn India,” said the spokesperson.
By choosing the 46-year-old Mr Thomson to replace Sir Bill, Cairn has gone for a younger man with considerable commercial experience. Sir Bill said: “Simon has been with Cairn for 15 years and has played an instrumental role in accessing the opportunities that Greenland offers the company as well as in the delivery of value from Cairn’s interests in India.”
The appointment surprised some in the City. Cairn’s exploration supremo Mike Watts has been deputy chief executive since March 2009. The 55-year-old was an obvious choice to replace Sir Bill.
One analyst who asked not to be named told Reuters: “I’m not sure the new CEO is that well known in the City.”
Asked whether Mr Watts had been passed over, the Cairn spokeswoman said: “Simon Thomson was the unanimous choice of the board and neither Mike Watts or anyone else was considered as a candidate.
“Given their complimentary skills and experience and their close working relationship Simon Thomson as chief executive and Mike Watts as deputy chief executive was seen as the best outcome.”
Cairn Energy’s finance director Jann Brown will become managing director in light of her widening responsibilities in areas like human resources.
Simon Copus, analyst at Deutsche Bank, told clients: “We view these changes to be a constructive step forward that is focused on energising the group for its next steps of growth.”
He described Simon Thomson as “energetic in personality”.
Shares in Cairn Energy closed down 7.6p at 403.3p yesterday.