Princess Diana’s brother – Earl Spencer – has shared a family photo of the pair as youngsters, hours before a report into how the BBC landed an interview with his sister is due to be released.
He tweeted the photo along with the caption: "Some bonds go back a very long way."
The report will explore how the BBC and journalist Martin Bashir landed the famous 1995 Panorama interview and is expected to be published later today.
The explosive chat – in which the princess made the claim there were "three of us in this marriage" – has come under scrutiny after Bashir mocked up fake bank statements which he allegedly used to gain access to Diana.
Lord Dyson has been spearheading the investigation, which will consider whether the steps taken by Bashir and the BBC were appropriate and to what extent those actions influenced Diana’s decision to take part in the interview.
The princess’s brother Earl Spencer has alleged Bashir showed him fake financial documents relating to Diana’s former private secretary Patrick Jephson and another former royal household member.
He also said the journalist had told outlandish and untrue stories about the Royal Family to get Diana onside, including that she was being spied on by the secret services.
Bashir was first introduced to Diana by Earl Spencer and sources close to the princess have told Sky News that without an introduction from her brother, Diana would never have met the BBC journalist.
Documents seen by Sky News show that Tony Hall, then managing director of news and current affairs and later BBC director-general, was aware Bashir had mocked up a bank statement using "information he had got from the highest level and made them into a graphic".
A press office log also revealed that when a journalist asked if Bashir had been officially disciplined, they were told he had not.
Numerous journalists had raised questions with the BBC about how Bashir secured the interview and the techniques he used, both before it was aired and five months later when a whistleblower informed the Mail on Sunday about the fake bank statement.
In a letter to the board of directors, Mr Hall had said: "I have talked to Martin at length about his reasons for compiling the graphic: He has none, other than he wasn’t thinking.
"I believe he is, even with his lapse, honest and an honourable man. He is contrite."
TV watchdog Ofcom has previously said it will not launch its own investigation but will follow the independent inquiry "closely".
Diana’s son Prince William has expressed support for the investigation, saying last year it should "help establish the truth behind the actions" that led to the programme.
A Panorama investigation into the interview has been delayed by the BBC before it was due to air on Monday due to a "significant duty of care issue".
Bashir, who was religion editor at BBC News, resigned last week citing health reasons.