LONDON (AFP) - Princess Diana rocked the monarchy when she leaked shocking details of palace life to author Andrew Morton, who told AFP the revelations are still causing damage 20 years after her death.
His 1992 book Diana: Her True Story - In Her Own Words laid bare her decaying marriage to Prince Charles, her suicide attempts and battles with bulimia.
But it also painted a bleak picture of life inside Britain's royal family.
Morton's book, which became a best-seller, shone an unflattering light on Prince Charles that still casts a shadow on the heir to the throne, as thoughts turn towards a post-Elizabeth monarchy.
Morton is convinced that that is something Diana intended.
"There's no question in her conversations with me and subsequently on television, when she talked about (how) Prince Charles wasn't fit to be king, that she always felt that Prince William should take on the role of the future king," he said in an interview in his London home.
"Today we find that a majority of people would rather see the crown go directly to Prince William rather than Prince Charles.
"Ain't going to happen, but that's public sentiment - and it's public sentiment in part, which has been influenced by Diana's life."
A poll conducted by YouGov found that the run-up to Thursday's (Aug 31) 20th anniversary of Diana's death in a Paris car crash had hit Charles's popularity.
Only a third of respondents said he had been beneficial for the royal family - down from nearly two-thirds four years ago.
Just 14 per cent want to see his current wife Camilla, Diana's nemesis during their marriage, as queen.
'DIANA WAS JUST DESPERATE'
"The anniversary has already opened old wounds for Camilla, people are being reminded of the fact that she was instrumental in ending this marriage that was described as a fairy tale," said Morton, who has released a revised version of his book to mark 25 years since its release.
Diana, who famously said there were "three people" in her marriage, contacted then-royal reporter Morton through friend James Colthurst in order to make public her anguish.
"She gave me the odd story, most notably about Prince Charles sacking his private secretary, and it gave her a sense of control and power, and she rather liked it," Morton explained.
"What I didn't realise at the time was that Diana was just desperate - nothing prepared me for the revelation that was to come," he added.
"Her husband Prince Charles was effectively living with another man's wife."
The author described the moment of hearing the first taped interview with Colthurst, who acted as an intermediary so Diana could maintain deniability when asked if she had met Morton.
"I was summoned to a working-man's cafe in London, and all around me, people were eating bacon and eggs and beans and chatting about the football scores, and I put these headphones on and I was transported into another world where Diana talked about her eating disorders, about desperate cries for help, about her loneliness, about her childhood, about her royal life, about Prince Charles.
"I found myself walking into a parallel universe."
'WORRIED ABOUT MY OWN SAFETY'
Morton used six tapes of interviews to write the biography, knowing that he was sitting on revelations that could tear apart the country's oldest and best-loved institution.
"I was very worried about my own safety and what was going to happen, it was incredibly nerve-wracking," he said.
"It's almost how you must feel like before you go over the top in the war... There's that gnawing fear and worry," he said.
Although it dealt a serious blow to the royal family, Morton believes the book and Diana's death five years later forced the institution into some much-needed changes.
"You've got a whole new generation taking the reins, William and Harry, and they exemplify many of the qualities and characteristics of Diana... they've become more human, more approachable.
After the Grenfell Tower fire in June in which some 80 people were killed, Queen Elizabeth II visited survivors and became "the consoler-in-chief".
It was a Diana-like public show of empathy.
"In a way, the royal family has come around to the way that she did business," he said.