BBC TV boss Danny Cohen in shock Corporation departure

The news has shocked many at the Corporation, where Cohen was one of its main cheerleaders during a critical year of negotiations with government concerning the future of the BBC.

Director-general Tony Hall paid tribute to Cohen in a statement, saying he had done an "extraordinary job" during his eight years in charge of the BBC's four television channels as well as BBC iPlayer.

However according to sources, Cohen and Hall were said to have disagreed on some issues, most notably how to handle the former Top Gear host Jeremy Clarkson.

Hall was believed to have been in favour of a more conciliatory approach to dealing with the presenter, while Cohen was less willing to tolerate his indiscretions. In the end the decision to fire Clarkson was taken by Hall.

According to a source close to Cohen, one factor in his decision to quit was his reluctance to implement a whole new round of cuts which is likely to result when the BBC's Royal Charter is renewed next year.

However, other BBC sources insist that the choice to leave was made entirely by Cohen who took the decision because he did not want to be subject to speculation. "TV is a gossipy world and he thought that if he was talking to other people it would get out. The timing may seem odd but there is no such thing as uninteresting timing when it comes to the BBC."

Cohen said in a statement: "After eight wonderful years at the BBC, it is time for my next big challenge. BBC Television is on brilliant creative form. I feel very privileged to have led Television for the world's finest public service broadcaster and to have worked with so many smart and talented people. In particular, I'd like to thank my fantastic team across BBC Television, all the people who have been involved with making our programmes in the last few years, my colleagues on the Executive Board and Tony Hall, who I admire greatly.

"In the last few weeks I've been approached about a number of exciting opportunities and I want to consider these in an open and transparent way.

"I'm very proud of the wide-ranging success of BBC Television under my leadership. In this period of intense competition we've reached 92 per cent of UK audiences every week, delivered outstanding channel services and built the number one digital service across the television industry in the BBC iPlayer. Throughout this time, we've delivered a fantastically rich slate of ground-breaking shows, thought-provoking ideas, national and international awards and global hits. We have made our audiences laugh, cry and think, and have made extraordinary imprints on our national culture and the BBC's international reputation.

"There has never been a more exciting time for television and digital media. I'm looking forward to taking up a new leadership role in this age of intense creative and technological innovation."

Tony Hall, Director-General, said: "Danny has done an extraordinary job over the last eight years at the BBC. In a world of intense competition and choice, he has further enhanced the BBC's reputation for quality programming that is full of ambition and creativity.

"Danny has led the incredible resurgence of drama on the BBC, having commissioned or overseen shows like Happy Valley, Poldark, Last Tango In Halifax, Wolf Hall, Top Of The Lake, Peaky Blinders, Doctor Who and the forthcoming Dickensian and War And Peace. He has also made an outstanding contribution to comedy and entertainment, with shows such as Cradle To Grave, Peter Kay's Car Share, Strictly Come Dancing, EastEnders and The Graham Norton Show. He also led BBC One's 2012 London Olympics coverage. That is one hell of a CV.

"He is one of TV’s great talents. I know everyone who has worked with Danny has huge admiration for what he has delivered for the BBC. I want to wish him well for the future."

After Cohen leaves at the end of November, Mark Linsey, Controller of Entertainment Commissioning, will take on his role until an appointment is made.