Brian May has stunned Queen fans by revealing he dated late singer Freddie Mercury's longtime companion before she became the rocker's muse.

A day after actress Lucy Boynton was cast as Mary Austin in the upcoming Queen biopic, the guitar great explains she was once his date.

May reveals to Yahoo! Music Freddie asked for permission to ask Mary out after she and Brian had decided they were better friends than lovers.

"Strangely enough, Mary was the girl that I picked out as somebody fabulous, and I was kind of going out with her," Brian explains. "Freddie came up to me one day and said, 'Are you serious with Mary? Can I ask her out?' And he did, and they were lovers for a long time."

Mercury and Austin's romance ended when the late singer revealed he was fond of guys, but they remained close until the star's AIDS-related death, and she was a major beneficiary of his fortune after his passing in 1991.

May insists Freddie's relationship with Mary is key to the Queen story and he was very careful to make sure filmmakers had picked the right actress to play her in the movie Bohemian Rhapsody.

"That's why we took so long to approve a script, because it has to tell the truth, and it has to be real," he adds. "It also has to be entertaining, because the last thing that Freddie would want is to have something dull out there, you know? But it has to tell the story as it was.

"It's a unique story, because Freddie was close to Mary. He was close to his men friends. He was also very close to us. We were such a tightly knit family, so in a sense, we were Freddie's closest family - because Queen lasted longer than any of our marriages!"

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