Crisis at the BBC: Timeline of events

George Entwistle (l) resigned as director general after just over 50 days in the job

Nick Pollard, the former head of Sky News, has delivered his report - commissioned by the BBC - looking at whether there were any failings in the corporation's management of BBC Newsnight's 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 - prompting accusations of a cover-up.

Since then, further allegations against Savile have emerged during a widespread police investigation, and Newsnight had to apologise after broadcasting a report that led to a Tory peer being wrongly identified as a paedophile. Following the second report, BBC director general George Entwistle resigned, after just weeks in the job.

Here is how events have unfolded:

19 Dec 2012: BBC criticised over Savile report

The inquiry into Newsnight's shelving of a report into sexual abuse by Jimmy Savile criticises BBC management but finds no evidence of a cover-up.

A separate report is critical of the Newsnight report which led to Lord McAlpine being wrongly implicated in child abuse allegations. The editor and deputy editor of Newsnight are to be replaced.

12 Dec 2012: Number of alleged Savile victims reaches 450

Police confirm that the number of alleged sex abuse victims of the late Jimmy Savile has reached 450. Officers on the Operation Yewtree investigation say 589 alleged victims have come forward during their investigation of offences committed by Savile and others.

22 Nov 2012: Hall appointed as BBC director general

Hall is widely credited with having brought financial stability to the Royal Opera House

The chief executive of the Royal Opera House and the BBC's former director of news, Tony Hall, is appointed as the corporation's new director general.

BBC Trust chairman Lord Patten says Lord Hall is "the right person to lead the BBC out of its current crisis". Lord Hall, who starts next March, says he is "committed to ensuring our news services are the best in the world".

15 Nov 2012: BBC makes payment to Lord McAlpine

The BBC settles with Lord McAlpine over his libel claim about a Newsnight broadcast which led to him being wrongly implicated in child abuse. The damages, agreed 13 days after the broadcast, total £185,000 plus costs.

"The settlement is comprehensive and reflects the gravity of the allegations that were wrongly made," the corporation said in a statement. The Tory peer had said it was "terrifying" to find himself "a figure of public hatred".

13 Nov 2012: Disciplinary action begins

The BBC begins disciplinary measures against some of those involved in the decision to run the Newsnight report on care homes in north Wales.

12 Nov 2012: Head of News steps aside

The BBC's director of news Helen Boaden and her deputy Stephen Mitchell "step aside" from their roles, pending the results of Nick Pollard's inquiry into the management of Newsnight's report into Jimmy Savile, which was dropped.

Head of Newsgathering Fran Unsworth becomes acting director of news, while the editor of the Today programme, Ceri Thomas, takes the acting deputy role.

The moves are part of what acting director general Tim Davie calls "getting a grip" on the organisation by creating a "clear line of command".

BBC Scotland director Ken MacQuarrie, who had been asked to look into what happened at Newsnight, finds that there was "ambiguity around who was taking the ultimate editorial responsibility for the report".

Meanwhile, MPs, including deputy Labour leader Harriet Harman, take issue with George Entwistle's severance payment of £450,000 which is a year's salary rather than the six months he is entitled to under the terms of his contract. Lord Patten issues a letter explaining the BBC Trust's decision.

Separately, Iain Overton resigns as editor of the Bureau of Investigative Journalism, an independent body whose reporter Angus Stickler led the Newsnight investigation into the Wales abuse allegations.

11 Nov 2012: Lord Patten urges BBC 'overhaul'

BBC Trust chairman Lord Patten says a "thorough, radical, structural overhaul" of the BBC is necessary in the wake of the director general's resignation. He adds a new director general will be chosen within weeks.

Before his departure, Mr Entwistle had commissioned a report from BBC Scotland director Ken MacQuarrie into what happened with the Newsnight investigation. He reports his findings that day.

10 Nov 2012 - 21:12: Entwistle resigns

George Entwistle resigns as BBC director general saying that "in the light of the unacceptable journalistic standards of the Newsnight film broadcast on Friday 2 November", he had decided it was "the honourable thing to do".

His 54 full days in post make him the corporation's shortest-serving DG.

The chief executive of BBC Worldwide, Tim Davie, is appointed acting director general.

10 Nov 2012- 08:34: Entwistle appears on Today

In an interview with the Today programme's John Humphrys, Mr Entwistle says he did not see the Newsnight report, which did not name Lord McAlpine but led to him being mistakenly implicated in child abuse at north Wales care homes, until after it had been broadcast.

He also said that he had not seen tweets prior to the Newsnight report which flagged up its content, nor a front page newspaper article on the morning of the programme which said the story was based on mistaken identity.

9 Nov 2012: BBC apologises for Wales abuse report

Lord McAlpine issued his response amid claims over abuse at a north Wales children's home

Former Conservative Party treasurer Lord McAlpine issues a denial over internet reports linking him to alleged historical child sexual abuse in north Wales, saying they are "wholly false and seriously defamatory".

Within hours, victim Steve Messham apologises for mistakenly identifying the peer, saying police had shown him a picture of his abuser but incorrectly told him the man was Lord McAlpine.

The BBC issues an unreserved apology for the part its Newsnight report played in Lord McAlpine being wrongly implicated in the alleged abuse and announces an "immediate pause" in all Newsnight investigations.

8 Nov 2012: This Morning ambushes Cameron

Live on ITV's This Morning, presenter Phillip Schofield hands Prime Minister David Cameron a list of names which Mr Schofield says have been mentioned online as paedophiles.

Mr Cameron, who does not look at the list, says he is "worried" that speculation about unproven allegations could lead to a "witch-hunt particularly against people who are gay" and advises anyone with evidence of abuse to go to the police.

6 Nov 2012: May announces police inquiry

Home Secretary Theresa May announces a new police inquiry, led by the head of the National Crime Agency, into allegations of child abuse in north Wales in the 1970s and 1980s.

Separately, Mrs Justice Julia Macur will investigate the terms of the Waterhouse abuse inquiry.

Steve Messham, who made the allegation which ended up implicating Lord McAlpine, meets the Welsh Secretary.

5 Nov 2012: Cameron pledges to look at abuse claims

The prime minister says he is appointing a "senior independent figure" to look into the way allegations of sexual abuse at north Wales children's homes in the 1970s and '80s were dealt with.

2 Nov 2012: Newsnight airs Wales abuse report

Newsnight broadcasts a report in which a man who was sexually abused when living in a children's home in north Wales in the 1980s, calls for a new investigation.

In the report, Steve Messham says that a leading Thatcher-era Conservative politician abused him a number of times. Although the programme does not name the politician, it leads to speculation on the internet, which either names or implicates former Treasury minister Lord McAlpine.

2 Nov 2012: Michael Crick tweets

Hours before that evening's edition of Newsnight, the programme's former political editor Michael Crick tweets "'Senior political figure' due to be accused tonight by BBC of being paedophile denies allegations + tells me he'll issue libel writ agst BBC".

He adds that the person - now known to be Tory peer Lord McAlpine - said he had not been contacted by the BBC for his response to the allegations.

The tweets by Mr Crick, who now works for Channel 4, follow an earlier one made by Iain Overton, editor of the Bureau of Investigative Journalism. Its reporter Angus Stickler led the Newsnight investigation.

In a now deleted post on the social networking site, which has been retweeted 1,574 times, Mr Overton writes: "If all goes well we've got a Newsnight out tonight about a very senior political figure who is a paedophile."

23 Oct 2012: Entwistle grilled by MPs

Mr Entwistle tells the culture select committee that the Newsnight investigation should not have been dropped. He is accused by MPs of a "lack of curiosity" after explaining why he did not ask director of BBC News Helen Boaden for further details on the Savile story when she mentioned it to him in 2011.

The director general also tells MPs that he asked Newsnight editor Peter Rippon to step aside because of inaccuracies in his blog, rather than solely to allow the Pollard review to be carried out.

22 Oct 2012: Newsnight editor steps aside

A Panorama Special: Jimmy Savile - What the BBC knew investigates the Savile child abuse scandal and examines the events around the dropping of the corporation's own Newsnight investigation into the subject.

The same day, Newsnight editor Peter Rippon steps aside for the duration of the Pollard inquiry into the dropping of his programme's report. The BBC also issues a correction to Mr Rippon's blog post of 2 October, saying it was "inaccurate or incomplete in some respects".

12 Oct 2012: BBC reviews launched

In the light of the ITV investigation and a slew of further allegations against Savile in the press, Mr Entwistle announces two inquiries regarding the sex abuse claims.

The first will look at whether there were any failings in the BBC's management of the Newsnight investigation relating to allegations of sexual abuse by Savile, including the broadcast of tribute programmes on the BBC, and will be led by former head of Sky News, Nick Pollard.

The second, led by former High Court judge Dame Janet Smith, will examine the culture of the BBC during the years that Jimmy Savile worked there.

3 Oct 2012: ITV investigation broadcast

ITV airs its investigation: Exposure, the Other Side of Jimmy Savile, in which several women allege he sexually abused them when they were teenagers.

2 Oct 2012: Newsnight editor blogs

Ahead of an ITV programme to be broadcast the following day, Newsnight editor Peter Rippon writes in a blog that his programme's investigation of Savile at the end of 2011 was dropped for editorial reasons after the CPS said that a case had not been pursued because of to lack of evidence.

He writes: "we had not established any institutional failure and I judged it weakened the story from a Newsnight perspective. I took the decision not to publish".

17 September 2012: Entwistle becomes BBC director general

George Entwistle takes over the BBC's top job, saying he is "the right man for the job" and will put programme makers and "outstanding creative originality" at the heart of the organisation.

4 July 2012: Entwistle announced as Thompson successor

The chairman of the BBC Trust, Lord Patten, announces that George Entwistle has been appointed to succeed Mark Thompson as director general of the BBC, a post he will take up in September on a salary of £450,000 per year.

December 2011: Newsnight shelves Savile investigation

A six-week BBC Newsnight investigation into claims that Savile abused youngsters is dropped. Tribute programmes to the presenter are aired over the Christmas and New Year period.

At the time, director of BBC News Helen Boaden is director of BBC News and George Entwistle is director of BBC Vision, with overall responsibility for TV programme commissioning and scheduling. Mr Entwistle will later tell MPs that the pair had a brief discussion about the Newsnight investigation but that he did not ask Ms Boaden for further details.

29 October 2011: Savile dies

Former BBC TV presenter and Radio 1 DJ Jimmy Savile dies at the age of 84, at his home in the Roundhay district of Leeds. He is buried the following month in the seaside town of Scarborough.