Princess Diana's biographer says it's possible she fell in love with the 'prince' version of Charles instead of the individual

• Princess Diana's biographer says she could have fallen in love with the "prince" version of Charles.
• Diana's friend reportedly asked her if she loved Charles before being interviewed for the biography.
• "Diana: Her True Story" was published in 1992.

Princess Diana's biographer says there was speculation over whether the late royal was truly in love with Prince Charles when he was writing her biography.

Andrew Morton worked closely with Diana for her biography, "Diana: Her True Story," published in 1992, and kept in contact with the royal after it was published.

The princess provided secretly recorded tapes to Morton, in which she spoke about her life and her relationship with Charles, to be used as source material for the book. Her involvement was kept secret until after she died in 1997.

"There's always been two schools of thought. One is that she fell in love with the figurehead, with the prince and not the individual," Morton told Insider.

"I would actually say she did fall in love with the prince because, at the end of the day, Prince Charles is a very charming, entertaining man. Was she a bit overruled by him? Yes. But did she feel a fellow feeling with him? I think that the answer is also yes," he said.

"But I mean, there's no getting away from the fact that he was in love with somebody else," Morton added, referencing Charles' affair with Camilla Parker-Bowles, now the Duchess of Cornwall.

Morton also said that some of Charles' friends were "quite skeptical" of Diana.

Meanwhile, one of Diana's friends reportedly called her to "double check" that she had loved the prince before being interviewed for her biography in 1991.

"It's a question I asked her and I asked her friends, and on one occasion, one of her friends actually rang her up and said: 'Did you really love Charles?'" Morton told Insider. "And she said: 'Yes, absolutely.' And she just double checked before I interviewed them."

Morton's book revealed intimate details of Charles and Diana's relationship, including that Diana was required to call him "sir" when they were dating and was only allowed to address him by his first name when they became engaged.

After the princess died in 1997, Morton released a revised version of the book: "Diana: Her True Story - In Her Own Words," and for the first time admitted that the biography had been created "with the full co-operation and input" from the princess.

Footage from the tapes was published in the 2017 National Geographic documentary, "Diana: In Her Own Words."

In the tapes, Diana can be heard saying her wedding day to Prince Charles was "the worst day of my life." She also described herself as being "a lamb to the slaughter" when she joined the royal family.

"If she was alive today, I'd still be saying she had nothing to do with the book," Morton said. "Unless of course she had subsequently said she had been involved."