Richard Dearlove, a career spy who joined the overseas intelligence service straight from Cambridge, will take over from the current chief, Sir David Spedding, when he retires in September. Robin Cook, the Foreign Secretary, had considered candidates from outside the service but concluded that Mr Dearlove, 54, was the most appropriate choice for the top post, the Foreign Office said.
Mr Dearlove, who joined MI6 at the age of 21, will step up from his job as director of operations and assistant chief.
The title of "C" has been in existence within Whitehall since the post was created in 1909 for the head of the Foreign Section of the Secret Service Bureau. The term entered usage because Commander Sir Mansfield Cumming signed all his correspondence as "C". To this day, all MI6 chiefs refer to themselves by the term in letters to the Prime Minister and other ministers.
Mr Dearlove will work closely with his opposite number at MI5, Stephen Lander, to combat international crime as well as the more traditional tasks of spying on other nations.
His career history published by the Foreign Office yesterday shows that he mixed active service abroad, in Prague,Washington and Geneva with spells of less glamorous administrative work at home.
A Foreign Office spokesman said: "Mr Dearlove's broad-ranging operational career has given him particular experience of working closely with national and international intelligence, security and law enforcement agencies."