Camilla Parker Bowles wasn't the royal family's first choice for Prince Charles.

The Prince of Wales dated the Duchess of Cornwall even before he married Princess Diana. However, their romance was a big "no" to the Firm because Camilla was considered to be a woman with "experience."

Dr. Piers Brendan clarified Camilla's "experience" in the documentary "The Royal House of Windsor."

"It was absolutely vital to have on the throne somebody who was a virgin," he said (as quoted by Express). "A future Queen must have no past."

Although the members of the royal family don't approve of Camilla for the future king, Prince Charles was very in love with her. According to journalist Christopher Wilson, the Prince of Wales was "red-blooded and passionate" and when he met Camilla there was "like a thunderclap."

"She was funny, she was outspoken, a bit outlandish, she'd lived a bit," author Penny Junor added. "And he was still very green behind the ears and he just fell for her big time."

Prince Charles had to choose a perfect woman by his side as the future Queen and this meant that Camilla's past was an obstacle for her. "I mean, there is no suggestion at all that Camilla was a loose woman, but she had had boyfriends," Junor added.

Sally Bedell Smith has made the same revelation in her biography "Prince Charles: The Passions and Paradoxes of an Improbable Life." According to her, the royals perceived Camilla as an "experienced" woman. 

In addition, they didn't see her as "aristocratic" enough for the future king. In fact, even Prince Charles' great-uncle Lord Mountbatten warned the royal about their relationship.

"Lovely for you two to have a fling, but this absolutely cannot end in marriage," Lord Mountbatten told Prince Charles.

Prince Charles and Camilla's romance ended when the prince traveled abroad for a royal duty. Camilla married Andrew Parker Bowles. However, the exes eventually rekindled their romance. In fact, Princess Diana reportedly learned about their affair weeks before their royal wedding.

According to sources, the late Princess of Wales wanted to call off the wedding, but it was too late. "Well, bad luck, Duch, your face is on the tea towel…so you are too late to chicken out,'" her sisters told her.