The chairman of the BBC’s governing board has called for radical change in the world’s largest broadcaster after it was plunged into crisis following the resignation of its chief executive in a sex abuse row.

Director-general George Ent­wistle quit on Saturday night, just 54 days into the job, after the flagship BBC programme Newsnight admitted it had wrongly implicated a politician in abuse at a Welsh children’s home.

His departure leaves the organisation in chaos as it struggles to restore trust in its journalism and battles the scandal surrounding Jimmy Savile, the late BBC TV star now alleged to have been a prolific child sex offender.

Chris Patten, the chairman of the BBC Trust, said there must now be a “thorough, structural, radical overhaul” of the way the BBC was run, although he said he would not be quitting over the row.

The allegations against Savile, who died last year aged 84, and the botched Newsnight report have left the BBC facing one of the most serious crises of its 90-year history.

“The wholly exceptional events of the past few weeks have led me to conclude that the BBC should appoint a new leader,” Entwistle said in a statement outside the broadcaster’s London headquarters on Saturday.

“To have been the director-general of the BBC even for a short period, and in the most challenging of circumstances, has been a great honour.”

The announcement came the day after Newsnight was forced to apologise for wrongly implicating a senior Conservative party figure in abuse at a Welsh children’s home in the 1970s.

The director-general admitted he had no knowledge of the show before it was aired, in itself a source of criticism, but said quitting was “the honourable thing to do” since he was ultimately responsible for all the BBC’s output.

He has been replaced by Tim Davie, a former Pepsi exec-utive who is currently the BBC’s director of audio and music, while the BBC Trust finds a more permanent replacement.

A major police investigation is currently underway into claims that Savile abused up to 300 children over a 40-year period, including on BBC premises.

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