In the fourth season of The Crown, there is a scene where Princess Diana (Emma Corrin) treats her husband, Prince Charles (Josh O'Connor), to an unexpected wedding anniversary present: a video of herself singing "All I Ask of You" from the musical The Phantom of the Opera. The recording is no joke: The princess is dressed in an elaborate Christine Daaé costume on the actual set of the West End production with a full orchestra accompanying her. Diana is proud of the feat, but Charles is not pleased by it.

In real life, the late royal was known to be a huge fan of the musical, and according to reports, she really did give her hubby this gift. Annie Sulzberger, head researcher for The Crown, told The Telegraph, "We did not make this up. There were a number of [press] reports on this, enough to make us feel comfortable including it in the show. It's a story that pre-existed the writing of the script."

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Princess Diana dresses up to attend a performance of The Phantom of the Opera at Her Majesty’s Theatre in 1986.

Sulzberger added that it's unclear exactly what Diana did for her performance; she could have mimed to the song or simply danced to it, as some accounts have suggested. "To minimize the number of witnesses, there is a chance they played a recording," she said.

But a 1988 report in The Washington Post claimed that the recording does indeed include Diana's original vocals.

For this, the seven-year itch anniversary, she presented Prince Charles with a video of her current favorite musical, "The Phantom of the Opera," and in it she sings for him a song from the show, "All I Ask of You." And she did this simply by renting the show's set at the theater in London's West End where it is playing and having her movements directed by the show's choreographer, Gillian Lynne. Diana didn't settle for second best. The show's composer, Andrew Lloyd Webber, was there to oversee her performance.

Webber later denied the claims to The Telegraph. A few of the princess's biographers—Penny Junor, Ingrid Seward, and Simone Simmons—and her former bodyguard were skeptical about the report too.

Still, the official Phantom Twitter account acknowledged the scene on the day Season 4 premiered, sharing a photo of Diana meeting the cast. "'All I Ask of You' was always one of her favourite songs, with her once making a private video on the Phantom's stage. Excited to see this moment in @TheCrownNetflix with the wonderful Emma Corrin," the caption read.

Corrin actually sang "All I Ask of You" during her audition process for the role of Diana, and it was that impromptu performance (over a YouTube karaoke track of the song) that helped her win the producers over, Vulture reported.

For the actual filming process, The Crown got the real West End Phantom set, as well as actors from the stage production and an orchestra. Corrin, a trained singer with a background in theater, worked with a voice coach to develop her version of Diana's singing voice. "I did about two [takes] and I had a complete panic attack, had a nosebleed. I had a proper, like, a proper breakdown," the actress told Vulture. But the cast and crew were very supportive of her.

Unfortunately, Diana's "All I Ask of You" footage is not available to the public, so we'll stick with Corrin's on-screen version for now.