EXCLUSIVE: Two construction workers apparently got up close and personal with Princess Diana.

British author Tom Quinn recently released a new book titled “Kensington Palace: An Intimate Memoir from Queen Mary to Meghan Markle,” where he spoke to those who worked for the British royals over the years. It was during his talks with palace insiders that Quinn learned some surprising stories about the Princess of Wales.

“It’s surprising,” Quinn told Fox News. “I was more surprised than anyone when I discovered -- you know, there are so many stories about the late Diana, Princess of Wales. I thought, ‘Well, there can’t be many more that people haven’t heard.’ But in talking to various people, I found some wonderful stuff.”

According to Quinn, Diana used to enjoy sunbathing in the buff in her rooftop garden of Kensington Palace, where she believed the area was safe from hovering helicopters and pesky paparazzi.

PRINCE WILLIAM ‘HAS FORGIVEN’ HIS FATHER PRINCE CHARLES ‘FOR THE MISTAKES OF THE PAST,’ ROYAL EXPERT CLAIMS

Princess Diana leaving Chelsea Harbour Club, London in November 1995. (Photo by Anwar Hussein/WireImage/Getty)

PRINCE WILLIAM, PRINCE HARRY’S ‘DEVASTATING BREAKDOWN’ REVEALED IN NEW BOOK: ‘I HAVE BEEN ASTONISHED’

“She loved sunbathing,” said Queen. “This was the ‘90s. There wasn’t so much worry about cancer scares and so on. She used to sunbathe on a flat roof at Kensington Palace.”

According to the book, Diana’s palace aides warned the royal that many choppers did have high-resolution binoculars. However, Diana felt secure in her personal haven away from the public eye -- at least until something went wrong.

“Somebody had done something with one of the screens,” Quinn explained. “There were small trees in troughs around the flat roof and she hadn’t noticed it had been taken away. So she stood up with no clothes on and then immediately realized two builders who were working a hundred yards away. She was eye to eye with them. They’d seen her standing up and no clothes on. And the two builders immediately just bowed and turned away.”

A footman later noted, “They may have just been builders, but they were gentlemen all the same.”

But not all the stories Quinn discovered about Diana, a royal who relished dressing up in disguise to enjoy a sense of normalcy outside of the palace, were comical. Palace insiders also alleged that Diana and her then-husband Prince Charles were often heard arguing from their Kensington Palace apartments.

ROYAL INSIDERS REACT TO KRISTEN STEWART'S 'OUT OF TUNE' CASTING AS PRINCESS DIANA

Prince Charles and Lady Diana Spencer. (Photo by Tim Graham/Getty Images)

KRISTEN STEWART TO PLAY PRINCESS DIANA IN UPCOMING MOVIE ABOUT ROYAL FAMILY

A former communications staffer alleged, “You could hear them rowing almost from the day they moved in.”

Quinn wasn’t surprised by the claims.

“They were almost maneuvered together because she was from a very ancient English family,” he explained. “And Charles needed someone who was young [who] could have children. I’m not sure they were well-suited, but they were maneuvered together by the royal establishment.

The quarrels were purportedly over Charles’ alleged mistress, Camilla Parker-Bowles.

“If you look at the film of the wedding day, there’s a tension and unease,” said Quinn. “… Camilla and Charles had a relationship before Diana and I think Diana rather naively thought that the relationship would end. It was never going to happen… Camilla actually encouraged [Charles] to marry Diana because they thought Diana would be complacent. She was timid. They thought she would just accept the fact that Charles and Camilla would carry on seeing each other.”

PRINCE WILLIAM SAYS HAVING CHILDREN WAS 'LIFE-CHANGING,' BRINGS BACK 'EMOTIONS' FROM DEATH OF PRINCESS DIANA

Camilla Parker-Bowles (left) and Lady Diana Spencer (later the Princess of Wales) at Ludlow racecourse to watch the Amateur Riders Handicap Steeplechase in which Prince Charles was competing. (Photo by PA Images via Getty Images)

PRINCE WILLIAM WRITES LETTER TO CHARITY HONORING PRINCESS DIANA ON BEHALF OF PRINCE HARRY AND HIMSELF

“They completely underestimated her,” Quinn continued. “In fact, someone said to me that if you look very carefully at the wedding film, you can see Diana glance across because Camilla was actually there in the church when they got married… You can see from the outset that Charles and Diana's marriage was doomed because the cracks were there from the beginning.”

The couple divorced in 1996. And while the relationship came to an end, Quinn said that her boyfriend Dodi Fayed gave her a sense of happiness during the last year of her life.

Diana passed away in 1997 at age 36 from injuries she sustained from a car crash in Paris.

“I think Dodi made the last year of her life happier than they would have been,” said Quinn. “The royal family certainly disapproved. The establishment was very nervous about this [relationship]. I think the royal family was in despair, to some extent, because this wasn’t something they could control. And Dodi was trying desperately to be accepted in royal circles.”

CHARLES SPENCER, PRINCESS DIANA’S BROTHER, OPENS UP HIS KITCHENS TO HELP MAKE MEALS FOR HEALTH CARE WORKERS

Dodi Fayed. (Photo by © Aaron Rapoport/CORBIS OUTLINE/Corbis via Getty Images)

CINDY CRAWFORD RECALLS BEING 'INTIMIDATED' WHILE MEETING PRINCESS DIANA

Quinn alleged that aristocratic advisors of the British royal family “looked down” at Fayed.

“I think they were slightly exasperated with the whole Diana situation,” she said. “I think they saw her, to some extent, as a bit of a loose cannon. They didn’t know what she would do next. And they felt it was unsuitable that she should be going out with Dodi.”

However, Quinn shared that Diana, who was free from an unhappy marriage, was eager for what the future held for her, both publicly and personally.

“The thing above all else that the royal family wants to try to do and feels it has to do is control every situation,” he said. “And they couldn’t with Diana… When Diana fell in love, it tended to be incredibly passionate. She lost all sense of restraint. And I think that happened with Dodi… But people really did underestimate her.”