The graphic designer who created documents for Martin Bashir has called for the former Panorama reporter to provide “answers” about his famous interview with Diana, Princess of Wales.

The BBC has said that Mr Bashir, now the BBC’s religion editor, is seriously ill with Covid-related complications.

The allegations centre on claims by Diana’s brother, Earl Spencer. He said he was shown “false bank statements” by Mr Bashir which were used to help gain access to Diana for the interview.

Graphic designer Matt Wiessler also criticised former BBC boss Lord Hall, who led the internal inquiry in 1996 into whether or not Diana was misled.

Lord Hall was director of BBC news and current affairs at time of the inquiry, which concluded that the graphic played no role in Diana’s decision to do the interview.

But the BBC’s board of governors was told, following the inquiry, there had been “steps to ensure that the graphic designer will not work for the BBC again”.

Mr Wiessler told BBC Radio 4’s Today programme he was “absolutely gobsmacked” to discover that “a board of governors meeting, there to look into what Martin had done” had made him “the scapegoat”.

“I don’t know how you can plausibly tell a story that a graphic designer is to blame.

“And I’ve been living with this for 25 years. And when I saw this, this decree that went out… I was pretty angry … because I thought it was utterly unfair.”

The name of the person who wrote that the “graphic designer will not work for the BBC again” is not published on the internal BBC document, which has just come to light.

But Mr Wiessler said of Lord Hall: “People in his position, who are on executive salaries, when push comes to shove and there is a real issue, they shouldn’t stand by the big scoop – they should stand by the truth.

“That’s why they get paid a lot of money.”

He added: “The person that needs to come forward is Martin Bashir. He’s the only one that has the answers.”

Former director general Lord Hall, who left the BBC earlier this year, said in a statement to Today that “the focus of the original investigation was whether Diana had been misled”.

He said “this and any new issues raised will no doubt be looked at by the BBC’s new inquiry”.

His comments come after new BBC boss Tim Davie confirmed there would be an independent inquiry into the events.

“The BBC is taking this very seriously and we want to get to the truth,” he said in a statement.

“We are in the process of commissioning a robust and independent investigation.”

The broadcaster is expected to set out more details of the new, planned investigation in the coming days.

Downing Street said that Mr Davie was right to order an independent investigation.

“This is the right course of action. As a public service broadcaster we expect BBC journalists to adhere to the highest standards,” the Prime Minister’s official spokesman said .

“The director general has set out that there needs to be an independent investigation into this and the Prime Minister believes that is the right course of action.”

Diana’s brother Earl Spencer alleges that he was shown “false bank statements” by Mr Bashir. He claimed these statements were used to help the reporter gain access to the princess.

The result was the explosive interview in 1995, in which Diana famously said of her relationship with the Prince of Wales: “Well, there were three of us in this marriage, so it was a bit crowded.”

Former BBC chairman Lord Grade said that there was “a very dark cloud hanging over BBC journalism” following the allegations.

He told BBC Radio 4 programme World At One: “The BBC is the gold standard of journalism in this country. For the BBC to be faking documents in the interest of getting a scoop raises very serious questions and the BBC needs to clean this up once and for all.

Mr Wiessler has previously called on the broadcaster to apologise.

He spoke about the impact the experience had had on his life after he was reportedly asked by Mr Bashir to create two bank statements in 1995. He claimed these falsely showed that members of the royal household were being paid by security services to spy on the princess.

Mr Wiessler told new ITV documentary The Diana Interview: Revenge Of A Princess: “I quite clearly felt that I was the one that was going to be the fall guy in this story.

“All I want is for the BBC in this instance to come forward and honestly make an apology. Because it’s had a huge impact.”

He claimed his flat was burgled soon after the interview and only two computer discs were taken – containing the back-up copies he made of the statements.

The earl has claimed that the internal inquiry into whether or not Diana was misled was a “whitewash”.

Also speaking to ITV’s The Diana Interview programme, Richard Ayre, the BBC’S former head of editorial policy, said Diana being happy with the way Mr Bashir obtained his interview “wouldn’t make any difference one way or the other”.

When asked about a note Diana allegedly wrote to the head of Panorama saying she was happy with the way she had been approached, Mr Ayre said: “But then if you, if you pursued this idea that he’d forged that document, I mean, I don’t see how her being happy that it would make any difference one way or the other really.

“Of course, she was happy because she was pleased the programme went out.”

The BBC said at the time that Diana had written a note saying she did not see the false bank statements and that they played no part in her decision to give the interview.

The corporation said it no longer has a copy of the letter.

The princess sent shockwaves through the monarchy after the interview, which included candid details about her marriage and Charles’s rumoured relationship with Camilla Parker-Bowles, who is now his wife.

Diana also questioned Charles’s suitability as king.

A month later, the Queen urged the separated couple to divorce, which they did in 1996.

The princess died in 1997 in a car crash in Paris.

– The second episode of The Diana Interview: Revenge Of A Princess airs on Tuesday on ITV at 9pm.