A "thorough, radical, structural overhaul" of the BBC is necessary in the wake of the resignation of the director general, BBC Trust chairman Lord Patten has said.

George Entwistle resigned as director general of the BBC after a controversial Newsnight report led to a former Tory treasurer being linked to abuse in children's care homes in the 1980s.

David Dimbleby, BBC commentator and a presenter of current affairs and political programmes, told Today presenter John Humphrys: "I can't understand why the director general of the BBC resigned."

"The BBC has a crisis of management of its own making Lord Patten should have a good close look at how the BBC is run," he added. "In my opinion, the BBC is still over-managed... I believe that good plain-speaking is what's needed."

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