The BBC will investigate claims that Diana, the late Princess of Wales, was shown fake bank statements to encourage her to take part in a televised interview.
Diana’s Panorama interview with Martin Bashir in 1995 is still one of the most-watched television interviews of all time, and included her famous statement that there were “three of us in this marriage”, referring to Charles’s affair with Camilla Parker-Bowles.
In a Channel 4 documentary released to mark 25 years since the interview, it was claimed that Bashir had fake bank statements made up by a graphic designer, to show that a former member of staff of the Earl Spencer, Diana’s brother, had become a paid informant.
The BBC confirmed the statements had been made, but said they had no bearing on Diana’s decision to do the interview.
However, the Earl Spencer called for an inquiry on Tuesday, saying the BBC had not grasped “the full gravity of this situation”.
A BBC spokeswoman said: “The BBC has apologised. We are happy to repeat that apology. And while this was a quarter of a century ago, we absolutely will investigate – robustly and fairly – substantive new information.
“We have asked Earl Spencer to share further information with the BBC.
“Unfortunately, we are hampered at the moment by the simple fact that we are unable to discuss any of this with Martin Bashir, as he is seriously unwell. When he is well, we will of course hold an investigation into these new issues.”
Earl Spencer had said: “If it were not for me seeing these statements, I would not have introduced Bashir to my sister.
"In turn, he would have remained just one of thousands of journalists hoping that he/she had a tiny chance of getting her to speak to them, with no realistic prospect of doing so."
The allegations came to light during a documentary which explored how the 1995 Panorama interview in Kensington Palace came about and whether Diana had regretted it.
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In a previous BBC statement, a spokesman said: “The BBC is being as open as we can be about events from a quarter of a century ago.
“Our records show the focus of the BBC's investigations into these events was whether or not the Princess of Wales had been misled, and they show that the BBC's key piece of information was the hand-written statement from the Princess of Wales, who said she hadn't seen the mocked-up documents and they had played no part in her decision to take part in the interview.
"None of this means the BBC won't properly look at issues raised. If anyone has substantial new information they would like to share with us, we are encouraging them to do so. While Martin is unwell, however, we are unable to progress this further."