Q&A: BBC crisis explained
Nick Pollard, the former head of Sky News, has delivered a report - commissioned by the BBC - looking at whether there were any failings in the corporation's management of the Newsnight investigation into allegations of sexual abuse by Jimmy Savile.
The programme did not broadcast its planned report last year, and weeks later BBC TV ran tributes to the late presenter - leading to accusations of a cover-up.
Here's the background to the crisis, which led to the resignation of the director general.
How did this come about?
In December 2011, Newsnight decided not to air an investigation into claims that Savile, a star BBC presenter from the 1960s to 1980s who had recently died, had sexually abused young people.
In October 2012, rival broadcaster ITV aired its own programme on the allegations, which added to a flurry of further accusations against Savile. This in turn led to mounting questions about why the Newsnight programme was dropped, and whether there was a cover-up.
A number of investigations were launched inside and outside the BBC. The editor of Newsnight, Peter Rippon, stepped aside on 22 October pending the result of an investigation by a former head of Sky News, Nick Pollard.
On 2 November, Newsnight aired a separate programme on alleged abuse at the children's home in Wales, in which a witness claimed that a Conservative politician abused him a number of times.
Though the programme did not name him, speculation on the internet either names or implicated former treasury minister Lord McAlpine. A week later, Lord McAlpine issued a denial, and Newsnight's witness apologised for the case of mistaken identity. The BBC then issued an unreserved apology. You can see a timeline here.
How has it affected broadcasts?
There was an "immediate pause" in all Newsnight investigations ordered when the problems with the 2 November programme became apparent. But other broadcasts on the BBC have carried on as before.
What is the BBC editorial chain?
At the time of the Newsnight investigation into Jimmy Savile, editors on the programme answered to Stephen Mitchell, deputy director of news and head of programmes. His boss was Helen Boaden, the head of news, who in turn answered to the director general.
When the investigation into the Savile programme was announced, Ms Boaden and Mr Mitchell were removed from overseeing coverage related to the Savile story. See a chart of the editorial chain of command here.
But following the story about the alleged abuse at children's homes in Wales, the two managers "stepped aside" from their roles, pending the results of Mr Pollard's inquiry. Head of Newsgathering Fran Unsworth became acting director of news, while the editor of the Today programme, Ceri Thomas, took the acting deputy role.
Why did BBC director general George Entwistle resign?
George Entwistle resigned as BBC director general on 10 November, citing the "unacceptable journalistic standards of the Newsnight film broadcast on Friday 2 November". He received a £450,000 payoff, and his 54 full days in post made him the corporation's shortest-serving DG.
The chief executive of BBC Worldwide, Tim Davie, was appointed acting director general. The corporation's new DG will be the chief executive of the Royal Opera House and the BBC's former director of news, Tony Hall, who starts in March.
What are the findings of the two investigations into Newsnight?
The Pollard inquiry into Newsnight's shelving of the Savile report criticised "chaos and confusion" in BBC management but found no evidence of a cover-up. The full report can be read here . The BBC Trust's separate investigation into Newsnight's 2 November film said there had been a failure by members of the programme's team to follow the BBC's own editorial guidelines.
What actions are being taken?
The editor and deputy editor of Newsnight are to be replaced. Head of BBC News Helen Boaden, who had stepped aside during the inquiry, will return to her post. The deputy director of news Stephen Mitchell has resigned and will leave the corporation next year.
Why is this important?
The BBC is a public service organisation, financed within the UK by a licence fee paid by British residents. Throughout its history it has built up a reputation for trust and reliability both within the UK and beyond. It has fiercely defended itself against outside interference, especially from the UK government. Its dominance, both because of its size and because of the reach of its output, has frequently come under criticism from commercial rivals.
What is the government's position?
Prime Minister David Cameron has referred to the problems facing the BBC as "very difficult, very serious", but has said he does not believe that the corporation is facing "an existential crisis". Culture Secretary Maria Miller said the Pollard report raised "serious questions around editorial and management issues at the BBC", and urged the BBC Trust to "help tackle these".
Is this the first such crisis at the BBC?
The BBC has been through serious crises before.
In January 2004 Gavyn Davies, the chairman of the BBC's board of governors, and Greg Dyke, the director general, both resigned in the wake of an inquiry that criticised the BBC's handling of a report about intelligence in the run-up to war in Iraq.
In 1987, another director general, Alasdair Milne, was forced out after a series of disagreements with the Conservative government of Margaret Thatcher.
The BBC has clashed several times with governments over coverage of conflicts involving British troops. In 1956, the Conservative government was upset by coverage on the BBC of divided opinion about the decision to recapture the Suez Canal from Egypt. Schemes to "discipline" the corporation were discussed, which are believed to have included the government taking editorial control of the BBC. Ultimately, there were no sanctions and the BBC's reputation for impartiality survived more or less intact.