Kate Middleton in a nurse costume enticed Prince William back after breakup

A new biography of the Princess of Wales describes the time she looked alluring to William while dressed in a costume for a 'Freakin Naughty' fancy-dress party.

While some obsessive royal watchers have accused Prince William of indulging in a rather unusual sexual fetish, with absolutely no evidence, it’s possible that the future king likes to engage in a more mainstream practice that can be silly, romantic and take place within the pleasures of a loving relationship.

That’s one possible takeaway from a certain revelation in a new biography of William’s wife, Kate Middleton, by royal author Robert Jobson, according to the Daily Mail.

The book, “Catherine, the Princess of Wales,” a chapter of which is excerpted in the Daily Mail, describes a scene in which Kate appears rather alluring in a nurse’s costume. She catches William’s eye at a “Freakin Naughty”-themed aristocrat’s costume ball, suggesting the possibility that the prince could be open to some fun, healthy role playing, as described by Men’s Fitness.

This scene took place when she and William and were young and in love. The couple, both now 42 and the parents of three children, were two years out from graduating from University of St. Andrews in Scotland, where they had begun dating in 2002.

However, in early 2007, the future king broke up with his future queen. As with a past split, William called off the relationship off due to his fear of commitment and his concerns about subjecting Kate to his high-pressure, high-visibility royal lifestyle, Jobson wrote.

Nearly 25, Kate seemed willing to bide her time with William, but the British media had begun to wonder if he’d ever propose marriage, leading her to be labeled “Waity Kate.”

William, who was serving as a second lieutenant in the army, suddenly canceled plans to join her at her family’s New Year’s gathering, Jobson reported. He then called to tell her they needed to take a break in their relationship, saying they both could benefit from “a bit of space” to “find our own way.”

William promptly celebrated the breakup by going out to a club with friends, proclaiming “I’m free,” while slipping into “a drunken version of the robot dance,” Jobson wrote.

For her part, Kate was devastated but didn’t shrink into despair, Jobson wrote. Rather than sit around and mope, the future queen and some girlfriends went on vacation to the Spanish island of Ibiza. When she returned, she and her younger sister, Pippa, began hitting nightclubs in London, attracting regular coverage in gossip columns through the summer.

After years as William’s loyal girlfriend, Kate seemed to be enjoying herself without him, Jobson reported. “Her heels were higher, and the outfits she wore — that sometimes bared her midriff or her spectacular legs — were far racier,” Jobson wrote. There also were were rumors that she was dating another eligible member of the aristocracy who also happened to be a shipping heir, while William was stuck in army barracks for much of the summer.

“Seeing photographs of his ex‑girlfriend having fun and looking sensational was a bitter pill,” Jobson wrote. “He soon began having serious second thoughts, though he realized that after the way he’d treated Catherine, it wasn’t going to be easy to woo her back.”

Jobson said William would need to give her “cast-iron assurances about their future together,” but he didn’t know when he’d get the chance to see her again.

Fortunately, he didn’t have to wait long, thanks to a mutual friend, Jobson wrote. Sam Waley-Cohen invited them to attended the “Freakin Naughty”- themed costume party at his family’s 17th-century manor house.

“The chemistry between William and Catherine did the rest,” Jobson said.

When Kate arrived, she was dressed as a nurse — maybe a “naughty” nurse, given the party’s theme.

William “made a beeline for her,” Jobson wrote. The two spent the first part of the night “deep in conversation before hitting the dance floor.” That’s where the couple ended up kissing, prompting friends to joke, “Get a room!”

William and Kate reconciled at the party, and she eventually moved in with him when he was stationed in Wales, where he’d spend the next five years working as an RAF Search and Rescue pilot, Jobson wrote. It would be another two years before William officially proposed, during a trip to Kenya in 2010. He popped the question as they stood “by the side of the turquoise waters” of Lake Alice,” Jobson added.

“The question wasn’t entirely unexpected, of course, but Catherine’s face lit up with a radiant smile as she said yes,” Jobson wrote.

During their engagement interview ahead of their 2011 royal wedding, journalist Tom Bradley asked William why he waited so many years to propose. The prince explained that he had tried “to learn from lessons done in the past.” William no doubt was alluding to his parents’ bitterly unhappy marriage, which began when his 19-year-old mother, Diana, wed then-Prince Charles, 31, after only meeting him 13 times.

“I wanted to give her a chance to see in, and to back out if she needed to, before it all got too much,” William said.