The BBC has recovered a letter handwritten by Diana, Princess of Wales, in which she insists she was not coerced by Martin Bashir into giving her landmark Panorama interview.
The letter, understood to have been found in BBC archives, will be handed to the independent inquiry into claims that Mr Bashir forged documents in order to win the Princess’s trust.
The BBC has come under increasing pressure over the scandal, with MPs demanding an explanation for the use of fake bank statements as well as an alleged cover-up.
Executives on Friday were said to be “relieved” at the discovery and many are hopeful that it will absolve them of any blame.
The BBC insists that the letter is genuine but a handwriting expert could be called in to confirm that it was written in the Princess’s hand.
The note had not been seen since 1996, when Mr Bashir was first accused of forging bank statements in order to clinch the interview, in which the Princess famously declared: “There were three of us in this marriage.”
Lord Hall of Birkenhead, the corporation’s former director-general, conducted an internal investigation into the allegations.
But as soon as the letter was received, the probe was abandoned, as it was deemed appropriate evidence that the Princess had not been misled.
There was a communal “sigh of relief,” one executive said. “We could all relax for Christmas. We had had a scare but had got through it.”
But incredibly, despite its significance, the letter was mislaid.
Mystery surrounded its whereabouts, fuelling speculation about its veracity and very existence.
A BBC spokesman said on Friday: “The BBC has now recovered the Princess’s original handwritten note which is referred to in our records from the time. We will pass it on to the independent investigation.
“We believe this is the original note passed to the BBC at the time.”
Mr Bashir is said to have commissioned two forged bank statements from a former BBC artist, which he showed to the Princess’s brother, Earl Spencer.
Veteran journalist Martin Bashir who is said to be 'seriously unwell'
The statements suggested that a former member of staff had betrayed him and was acting as a paid informant. One appeared to show that he had been paid £4,000 by News International and the other, that he had pocketed £6,500 from a mysterious Jersey-based outfit called Penfolds Consultants.
The information so impressed Earl Spencer that he orchestrated a meeting between the reporter and his sister.
The BBC has insisted that the Princess never saw the forged statements and that they had no bearing on the interview.
It has promised a “robust” independent inquiry, with which Mr Bashir is expected to cooperate, despite being in recovery from a quadruple heart bypass.