Princess Diana singing The Phantom of the Opera: the story behind the "All I Ask Of You" performance

The Crown has long worn its stagey origins on its sleeve – it was, after all, a series that is built on creator Peter Morgan's hit play The Audience.

This new season, released over the weekend, is no exception – not only does Princess Diana (a wonderful turn by up-and-coming actress Emma Corrin) have a song and dance to Billy Joel's "Uptown Girl" on stage at the Royal Opera House (with the front of London's Lyceum Theatre standing in for establishing shots) and in a special turn, Diana channels her inner Christine to present an unusual anniversary gift to Prince Charles.

Appearing in the ninth episode of the new series, Diana shows her husband and future king a recording of herself singing one of The Phantom of the Opera's most iconic tunes, "All I Ask Of You" for their seventh wedding anniversary in 1988. She says that she had recorded it on stage in the West End, specially taped for her hubby.

According to interviews with the Netflix show's head of research, Annie Sulzberger, Diana was an avid Phantom fan, seeing it on multiple occasions and meeting its composer Andrew Lloyd Webber. Lloyd Webber even tweeted about his excitement seeing Corrin singing the piece in the show.

The Crown's historical veracity has always been slightly dubious (a pinch of salt is very much required) but researchers claim that Diana really did go to the West End and had the set to herself, with Lloyd Webber appearing. Phantom was (and still is!) a massive hit with audiences, having premiered less than two years before the anniversary and playing to packed out audiences.

What Diana actually did while on stage is slightly less certain (we've reached out to the Phantom team to see if they know more) but The Crown producers decided to use Corrin's singing voice to its full effect and have her take on the number in person. Corrin also said to Morgan during auditions that she adored the long-running musical.

Indeed, according to producer Oona O'Beirn, the London production's orchestra at Her Majesty's Theatre is actually playing during the recording seen on The Crown, taped before the musical's closure in March.

Charles' reaction in the show was not all that enthusiastic, but, honestly, we are big fans.

Meeting Princess Diana on the first of her several visits to @PhantomOpera. She was a great lover of live theatre and I'm looking forward to seeing Emma Corrin's take on 'All I Ask of You' in @TheCrownNetflix. – ALW #TheCrown pic.twitter.com/QPlIYnMQZJ