In November 1995, Princess Diana gave one of the most famous and controversial television interviews in royal history. 

She spoke to BBC journalist Martin Bashir about her marriage, life inside the Royal Family, her eating disorder and her struggles with the press, in a sit-down chat that was watched by more than 20 million Britons alone. 

She'd agreed to the interview to 'set the record straight' after incessant tabloid speculation about her relationship with Prince Charles.

But 25 years later, the BBC and Bashir are under investigation, accused of lying and tricking Diana into going on camera.

We'll get to that in a minute, but first let's go back to 1995. 

What did Diana say during the interview? 

The interview was said to be the 'final straw' for Charles and Diana's marriage, with the couple announcing their divorce the following year. 

When asked about their marriage she famously told Bashir, "there were three of us in this marriage, so it was a bit crowded" referring to Charles' relationship with Camilla Parker-Bowles. 

Watch a snippet of the interview below. Post continues after video.

She also revealed that she had been "in love" with someone else at one point during their marriage, referencing her relationship with James Hewitt, a former household cavalry officer in the British Army. 

She spoke openly about her mental health, her struggles with bulimia - describing it as a "symptom" of a bad marriage - and her post-natal depression after the birth of Prince William. 

She also spoke about the Royal Family's opinion that she was a "non-starter" because she didn't follow the "rule book."

What was the reaction in 1995?

It was unprecedented. The interview's revelations painted the monarchy as cruel and oppressive, and gave the public more insight into the behind-the-scenes of the institution than ever before.

Some royal experts suggested it plunged the monarchy into the greatest crisis since the abdication of King Edward VIII in 1936, who threw in the throne to marry a divorced American socialite. 

It was also, however, the first time Diana had a major falling out with her eldest son William who was "livid" and teased at school because of it. 

Bashir managed to secure an interview that became the envy of every journalist in Britain. Image: BBC.

"He felt really bad for his mum because of what she had gone through, but he was furious with her. People at school were calling her all sorts of names. The weekend after it went out they had a big row at Kensington Palace. William was furious and Diana was distraught. I was there the day after she spoke to him and Diana was in a terrible state," Diana's friend Simone Simmons told Vanity Fair. 

Within a month of Diana's interview her press secretary had resigned, and the Queen had sent Charles and Diana a letter urging the couple - who had been separated since 1992 - to divorce quickly. 

The 1996 investigation.

For some context, it was Diana's brother Charles Spencer who introduced Diana to journalist Martin Bashir after being courted by him. 

Spencer was shown fake bank statements that supposedly proved that palace courtiers had been selling stories to the press about the princess, preying on fears Diana already had in order to convince her to agree to the interview.

The interview become infamous. Image: BBC.

The interview catapulted Bashir to fame and he won awards for the BBC Panorama special, but his own company questioned how he convinced the princess to agree to such an intimate chat, and opened their own internal investigation in 1996.

Despite Bashir's use of mocked up financial records, the inquiry concluded that Bashir had done nothing wrong stating, "The BBC has been able, independently, to verify that these documents were put to no use which had any bearing, direct or indirect, on the Panorama interview with the Princess of Wales."

What's happening now, in 2020?

In November 2020, British station ITV aired a documentary, The Diana Interview: Revenge of a Princess, featuring an interview with Matt Wiessler, the designer who Bashir asked to mock up the documents.

He told the program, "Martin asked me to make up a couple of bank statements that he needed the following day. And he did say they were going to be used as copies. So on that night, I was just making some props for filming purposes".

But Wiessler says he was then used as a scapegoat by the BBC who punished him, and let Bashir off the hook so as to not affect the integrity of the now famous interview.

Journalist and director behind the documentary, Andy Webb, obtained internal BBC documents through the Freedom of Information Act that explain the incident in detail. 

The documents prove that the inquiry cleared Bashir, letting him off the hook by saying he "wasn't thinking" while punishing Wiessler by stating he'd "never work for the BBC again."

As Weissler told BBC Radio 4, "I couldn't believe it when I saw that FOI release. I was absolutely gobsmacked that in a board of governor meeting, that was there to look into what Martin had done, I was made the scapegoat.

"I don't know how you can plausibly tell a story that a graphic designer is to blame for using copied documents as forgery, and I've been living with this for 25 years."

Diana's brother commented on the findings on Twitter, explaining that while he knew that Bashir had shown him fake bank notes, he was unaware that the BBC not only knew, but that they "covered it up."

2/2 ... what I only found out 2 weeks ago, thanks to journalist Andy Webb’s persistent use of the Freedom of Information Act, is that the BBC also knew. Not only knew about it, but that they covered it up.

— Charles Spencer (@cspencer1508) November 8, 2020

On Wednesday Director-General of the BBC Tim Davie announced that the broadcaster had commissioned an independent investigation into the incident, to be led by former judge John Dyson.

The investigation will take a look to see if the steps taken by both the BBC and Bashir, now 57, were appropriate, and to what extent those actions influenced Diana’s decision to give the interview at the time. 

She died in a car accident in Paris just two years later.

Bashir, who is currently the BBC News religion editor, is yet to make a statement because he's reportedly "seriously unwell" with complications from coronavirus, reports the BBC.

Feature image: BBC Panorama.