Princess Diana secretly authorized the publishing of Andrew Morton’s book “Diana: Her True Story.” But it was only years after her death that this detail became known to the public.

In the BBC Radio 4 series “Images of Diana,” journalist Natasha Kaplinsky said that the controversial book shattered the image of her fairytale marriage to Prince Charles. In Morton’s book, the Princess of Wales also referenced her eating disorder, self-harm, and Prince Charles’ adultery.

“Nobody knew at this point that she had given you permission, and she was directly involved,” Kaplinsky said.

Morton echoed the journalist’s statement by saying that he was like a fairground boxer who took all of the blows after the book was released. But the public didn’t know that all of the information he wrote in “Diana: Her True Story” came straight from the horse’s mouth.

The royal author said that he didn’t want to reveal Princess Diana’s identity because he made an agreement with her.

“Well, she hadn’t thought it through. I mean, I could have named her on day one. You know, it’s a gentleman’s agreement. We were going to give her deniability, so we wouldn’t say she said this to me, we would interweave her quotes in the text as told to friends and so on,” Morton said.

During their discussions, Morton reportedly told Princess Diana that the book isn’t objective but slanted because it comes from the late royal’s point of view and perspective of the story and Prince Charles.

“The libel lawyer said to us, ‘You can’t possibly say that Prince Charles and Camilla Parker-Bowles committed adultery because you weren’t in the bedroom. So, we ended up saying ‘they had a secret friendship’, but everyone worked it out from that,’” Morton revealed.

“Diana: Her True Story” was published in 1993, one year after Princess Diana and Prince Charles’ separation and three years before their divorce was finalized.

princess diana
Britain's Princess of Wales arrives at her London health club. Johnny Eggitt/AFP/Getty Images)