LONDON (AFP) - A former BBC chief who was criticised for his "woefully ineffective" probe into journalist Martin Bashir's deception in securing a bombshell interview with Princess Diana has resigned as chairman of Britain's National Gallery.
Mr Bashir tricked the princess into giving a 1995 BBC television interview in which she lifted the lid on her troubled marriage to Prince Charles, an independent investigation concluded last Thursday (May 20).
Mr Tony Hall, who had led an earlier investigation into the interview and was later named head of the BBC, said he had "today (May 22) resigned as chair of the National Gallery".
He added in a statement released by the world-renowned London gallery: "As I said two days ago, I am very sorry for the events of 25 years ago and I believe leadership means taking responsibility.
"I have always had a strong sense of public service and it is clear my continuing in the role would be a distraction to an institution I care deeply about."
Retired senior judge John Dyson said Mr Bashir commissioned fake bank statements that suggested some of Princess Diana's closest aides were being paid by the security services to keep tabs on her.
Mr Bashir then showed them to Princess Diana's brother Charles Spencer, in a successful bid to convince him to arrange a meeting between himself and Princess Diana and earn her trust.
Questions have long been asked about how Mr Bashir convinced her to talk on the BBC's flagship Panorama programme in November 1995, which was watched by a record 22.8 million people and won a string of television awards.
In it, she famously said there were "three people" in her marriage - Prince Charles' longtime mistress and now wife Camilla Parker Bowles was the third party - and also admitted adultery.
Mr Bashir, now 58, was little-known at the time of the interview but went on to have a high-profile career on United States television networks, and interviewed stars such as Michael Jackson.
He returned to work for BBC as religion editor until he stepped down last week, citing ill health, just hours before the Dyson report was submitted to BBC bosses.
On Sunday, he apologised to Princess Diana's sons Prince William and Prince Harry but said claims linking his actions to her death were "unreasonable".
A 1996 internal inquiry by Mr Hall cleared Mr Bashir of wrongdoing, but Mr Dyson called that probe "flawed and woefully ineffective".
In particular, it did not ask Princess Diana's brother for his version of events, Mr Dyson said, lambasting it for failing to scrutinise Mr Bashir's actions properly.
"If they had been able to test Mr Bashir's account by asking him to comment on Earl Spencer's detailed account, it is very unlikely that they would have believed him and concluded that he was an 'honest and an honourable man'," he wrote.
Mr Hall admitted that the probe "fell well short of what was required", and said he was "wrong to give Martin Bashir the benefit of the doubt".
Prince William said the interview had made "a major contribution" to the demise of his parents' relationship, while the BBC's "woeful incompetence" in uncovering the truth had "contributed significantly to her fear, paranoia and isolation" in her final years.
Princess Diana died in a high-speed car crash while being chased by paparazzi photographers in 1997.
Mr Hall took charge of the BBC in 2013, and stepped down last year.