Princess Diana and Freddie Mercury once went partying together at a gay club, book claims

Princess Diana shook the British monarchy to its core, and a 2013 book claims she even partied at a gay bar in London with a group of friends that included Freddie Mercury.

Book "The Power of Positive Drinking" claims that the People’s Princess and Queen’s frontman had a wild night out on the town. It's believed to be have happened in 1988, when her marriage to Prince Charles was already on the rocks.

The book’s author is 80's British TV star and model Cleo Rocos, who was part of the group that ventured out to the gay nightclub.

British comedian Kenny Everett was also supposedly there. The book claims the group dressed Princess Diana in an army jacket, black cap and sunglasses and headed to the Royal Vauxhall Tavern in south London.

According to her account, no one recognized the royal at the club and Princess Di even ordered drinks at the bar herself.

"When we walked in . . . we felt she was obviously Princess Diana and would be discovered at any minute," Rocos wrote. "But people just seemed to blank her. She sort of disappeared. But she loved it."

Earlier in the day, the group had gotten buzzed off of champagne while watching "The Golden Girls" reruns. After asking her friends what their plan for the evening was, Princess Diana insisted that she be allowed to go with them to the gay club, with Rocos noting that she was "in full mischief mode."

"Let the girl have some fun!" Mercury insisted.

If true, we now know where Prince Harry got some of that famous mischief from.