The careers of at least four staff - including Killick - suffered because they raised concerns about Bashir. Full-time freelance graphic designer Matt Wiessler had to leave the industry because his reputation had been so badly damaged.

Wiessler had drawn up the forged bank documents at Bashir’s request under the belief they were simply to illustrate an upcoming story. Bashir really used them to dupe Diana’s brother, Charles Spencer, into arranging an interview with his sister.

Wiessler realised he may have been misled while later watching the Panorama interview, and contacted Killick to relay his fears.

Killick then questioned Bashir during an encounter in the BBC canteen. Unhappy with Bashir’s answers, he and two others took their concerns to Panorama editor Steve Hewlett but were shouted at and dismissed. Hewlett later claimed Killick was motivated by jealousy.

“Within 24 hours I was taken aside and told that I was being disloyal and would be leaving the program,” Killick said on Friday.

The BBC’s press office was also instructed to smear Killick and other concerned colleagues when Fleet Street reporters got in touch with questions about how Bashir’s Diana interview came to be. Lord Dyson did not determine who authorised the campaign to discredit the whistleblowers.

Killick said the BBC must determine who was responsible. He also said the broadcaster’s apology to the royal family and to the unfairly maligned BBC staff did not go far enough.

“A lot of people were hurt in Diana’s camp and the BBC camp, and I’m not sure that a generic apology gets you home,” he said.

“I’m looking far more for some of the others. Take the graphic designer [Wiessler], who never worked again. What do you do to compensate somebody whose career has been destroyed? The BBC has to think further than a broad-brush apology to make things right.”

Wiessler on Friday described the BBC’s apology in a letter delivered eight hours after Lord Dyson’s report was released as “too little, too late”.

“I just feel that, still, there is this culture in the BBC that the little people...don’t really need to be addressed and only under duress do we get some sort of apology and acknowledgement,” he said.

“But, not a really fitting response for the 25 years that I’ve been sitting, waiting for people to stop calling me a forger and a leaker.”

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The perpetrator of a break-in at Weissler’s London home after the Diana interview aired has never been found. Just two items were stolen: discs of the graphic work he had created for Bashir.

Wiessler is currently being represented by London law firm SMB.

Former Panorama reporter Tom Mangold, who was also discredited by the BBC, has not ruled out suing his former employer.

“We haven’t decided yet,” he told BBC TV on Friday. “But I think we’ll take advice on this and think very carefully about it. It was a very unpleasant period.”

Tony Hall, the BBC executive who conducted an inquiry into the Diana interview in early 1996, has apologised for his role in the saga. That probe cleared Bashir, even though Hall knew by then that Bashir was a liar.

Hall went on to become the BBC’s director general between 2013 and 2020.

Bashir quit the BBC in the late 1990s but returned as its religion editor in 2016. He resigned last week, citing ill-health.

Prime Minister Boris Johnson said he was “obviously very concerned” about Lord Dyson’s findings.

“I can only imagine the feelings of the royal family and I hope very much that the BBC will be taking every possible step to make sure nothing like this ever happens again.”

Johnson, a former journalist, was once fired from The Times newspaper for fabricating quotes.

The BBC did not comment on Friday.