LONDON • Princess Diana rocked the monarchy when she leaked shocking details of palace life to author Andrew Morton, who told Agence France-Presse that the revelations are still causing damage two decades 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 her battles with bulimia.

It also painted a bleak picture of life inside Britain's royal family.

The book, which became a bestseller, shone an unflattering light on Prince Charles that still casts a shadow over the heir to the throne.

Morton is convinced that this is something Princess 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 Prince William should take on the role of the future king," he said in an interview at his London home.

He noted that "a majority of people would rather see the crown go directly to Prince William".

According to a YouGov poll, Prince Charles' popularity has taken a hit in the run-up to the 20th anniversary of Princess Diana's death. She was killed in a car crash in Paris on Aug 31.

Only a third of the respondents said Prince Charles 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 (nee Parker Bowles) as queen.

"The anniversary has already opened old wounds for Camilla - people are being reminded of the fact that she was instrumental in ending this marriage described as a fairy tale," said Morton, who has released a revised version of his book after 25 years.

Although it dealt a serious blow to the royal family, he believes his book and Princess Diana's death five years later forced them to make 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," he said.

After the Grenfell Tower fire in June, which left some 80 people dead, Queen Elizabeth II visited survivors and was "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.

AGENCE FRANCE-PRESSE