The corporation has pledged to reopen an investigation into the interview with the royal, an appearance which has secured a place in modern royal history after she alluded to Prince Charles’s relationship with Camilla Parker Bowles.
The appearance was brokered by Martin Bashir, who is currently the broadcaster’s religion correspondent. He is alleged to have forged bank documents to convince Princess Diana’s brother, Charles Spencer, to promote the idea to his sister.
In a statement, the broadcaster’s director general Tim Davie said: “The BBC is taking this very seriously and we want to get to the truth.
“We are in the process of commissioning a robust and independent investigation.”
A spokesperson for the broadcaster added that Mr Bashir is suffering with Covid-related complications, and is presently too ill to respond to the allegations.
The interview in 1995 - which came after her separation from the future King - became one of the media moments of the decade when the Princess of Wales told the BBC “Well, there were three of us in this marriage, so it was a bit crowded.”
In the weeks before the programme, Earl Spencer was approached by Mr Bashir and, in what are believed to be previously unrevealed details, he claims he was shown “false bank statements” that related to alleged payments made to two members of the royal household by the security services.
Whether other false documents relating to a former employee of the earl were produced was the subject of a BBC investigation at the time – as it tried to determine whether or not the princess had been misled – with a key piece of evidence, a note, suggesting she had not.
However the broadcaster has since said it no longer holds a copy of the note in question.
Former BBC chairman Lord Grade said that there was “a very dark cloud hanging over BBC journalism” following the allegations.
“We’ve got to get into the timeline of who knew what, when. Was the Diana letter also a forgery is the question that needs to be asked?”, he told BBC Radio 4’s The World At One.
“There may well be very good answers and the BBC may well come out of this absolutely clean.
“But there are so many questions being raised. There’s only one way to clear this up and that is with an independent inquiry to be published.”
Lord Grade added: ““The BBC is the gold standard of journalism in this country. For the BBC to be faking documents in the interest of getting a scoop raises very serious questions and the BBC needs to clean this up once and for all.
“Was it known by those editorially in charge of the BBC at the time that forged bank statements had been used or were tried to be used?
“Who knew and who knew when and was it covered up at the time? This is a very, very serious matter for the BBC, which holds itself in high esteem.
“It calls power to account in this country. It’s the first one to call for independent inquiries when there’s wrongdoing however long ago.
“But when it comes to the BBC itself being under question, the rules seem to change somewhat.”
It comes after the graphic designer who mocked up the documents allegedly used to secure the interview with Diana called on the broadcaster to apologise to him after claiming he had been made into “the fall guy”.
Matt Wiessler claimed the documents he was asked to produce falsely showed that members of the royal household were being paid by security services to spy on the princess.
He told ITV documentary The Diana Interview: Revenge Of A Princess his work dried up after the incident, and he left the industry soon after.
Mr Wiessler said: “I quite clearly felt that I was the one that was going to be the fall guy in this story.
“All I want is for the BBC in this instance to come forward and honestly make an apology. Because it’s had a huge impact.”
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