One of myth, I'd slightly like to be is Freddie and Kenny Everett dressed Princess Diana up as a man, and took her to a gay bar. Whether it actually happened or not is still a mystery, but various people have spoken about it. In Cleo's book
The Power of Positive Drinking, she claimed that the group were having champagne at Kenny’s home, before Diana asked about their plans for the rest of the evening. They said they were heading to a well known gay bar in London – and Diana is believed to have asked if she could join them. Kenny then allegedly dressed Diana up in his clothes, and Rocos claimed that she looked like "a rather eccentrically dressed gay male model." Cleo wrote: "Diana and Freddie were giggling, but she did order a white wine and a beer. Once the transaction was completed, we looked at one another, united in our triumphant quest. We did it! "When we walked in… we felt she was obviously Princess Diana and would be discovered at any minute. But people just seemed to blank her. She sort of disappeared. But she loved it."
Cleo elaborated on the story in her other book
Kenny and Me: Bananas Forever, in which she revealed the pair would watch Golden Girls together. "Freddie said, 'Go on, let the girl have some fun.' […] Scrutinising her in the half light, we decided that the most famous icon of the modern world might just – just – pass for a rather eccentrically dressed gay male model…"We inched through the leather throngs and thongs, until finally we reached the bar. We were nudging each other like naughty schoolchildren."
Various websites mention it, including Smooth Radio when it was part of an Urban Myths program.
https://www.smoothradio.com/artists/queen/freddie-mercury-princess-diana-vauxhall-tavern/