The BBC says it has recovered a note written by Diana confirming false bank statements had no role in her decision to participate in her 1995 Panorama interview.
Her brother Charles Spencer alleges journalist Martin Bashir used the fake documents to persuade the Princess of Wales that two of her senior courtiers were selling information about her – and therefore her best course of redress was to speak out in an interview with him.
The corporation had said a copy of the princess’s note was no longer in its possession and could not be produced for a 2007 Freedom of Information request – although its existence was documented in BBC records.
Diana’s document refers to mocked-up bank statements which the corporation has said Mr Bashir, who interviewed her, admitted commissioning as he tried to gain access to the princess.
It is understood the journalist was found to have “done wrong” at an internal inquiry in 1996, but it is not known what sanction, if any, he faced.
The BBC said the note confirms the princess had not seen the false financial documents ahead of her 1995 Panorama interview and they played no part in her decision to speak on camera.
The fake bank statements relate to a now ex-employee of Earl Spencer, but he has accused Mr Bashir of showing him other made-up documents, relating to members of the royal household, to ingratiate himself with Diana.
The development comes after the BBC announced it would hold an independent investigation into the allegations.
In a statement, the corporation said: “Following the announcement of the independent investigation, 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.
“As there has been a lot of commentary about this note and journalists have asked about it, we thought it appropriate to put on record that we’ve now recovered it.
“We will set out further details of the independent investigation shortly.”