The Crown fact-check: Did Prince Charles really date Diana's older sister Sarah Spencer?

Tina Brown, in The Diana Chronicles, describes Sarah being pleased that Charles was "squiring her around"; she "received a flattering stream of invitations to Windsor and Balmoral". It does not appear to have been a passionate love affair, but perhaps Sarah was being considered for a royal match.

In November of that year Sarah invited Charles to shoot at the family home at Althorp. This seems to have been where Diana, then a 16-year-old schoolgirl, met Charles properly for the first time, or perhaps the first time since she'd been a little kid. As Tina Brown puts it: "She registered on Charles's radar only as a 'jolly' and 'bouncy' younger sister of Sarah."

But as she adds (somewhat hyperbolically), for Diana "seeing Prince Charles for the first time since her childhood was a 'whoomph' moment of her own. Once she had caught sight of the number-one royal bachelor striding with his Labrador through a ploughed field with the guns and beaters and dogs, there was no other rival for her heart."

Why did Sarah and Charles split up?

It seems to have come down to a disastrous incident in early 1978 – not that this is covered by The Crown.

In February, Sarah had accompanied Charles on a ski trip to Klosters in Switzerland, and the press had caught on and followed them there; Sarah made friends with a couple of journalists (Nigel Nelson and James Whitaker) – and back in London over lunch she apparently made the tactical, thoughtless error of confiding in them.

According to the journalists, she told them all about her days of underage drinking, her expulsion from school, and her struggles with anorexia.

As Tina Brown writes: "Sarah herself realised her mistake as soon as the words were out of her mouth. She muddled things more by trying some damage control suggesting that Whitaker's interview had been obtained by foul means. This did not play well."

In response to that accusation, Whitaker published even more damaging quotes under a pseudonym, including the remark from Sarah: "There is no chance of my marrying Prince Charles. He is a fabulous person but I am not in love with him, and I wouldn't marry anyone I didn't love, whether he were the dustman or the King of England. If he asked me I would turn him down. Prince Charles is a romantic who falls in love easily. But I can assure you that if there were to be any engagement between Prince Charles and me it would have happened by now. I am a whirlwind sort of lady, not a person who goes in for a long, slow courtship. Our relationship is totally platonic."

Sarah continued to scramble. Having been warned that this quotation was about to be published in the magazine Woman's Own, she alerted Charles in advance to what was coming. His response, apparently, was delivered after a pause and with "deadly coldness": "You've just done something extremely stupid."

And that was that for Sarah and Charles.

• For the latest news and expert tips on getting the best deals this year, take a look at our Black Friday 2021 and Cyber Monday 2021 guides.

Wasn't it awkward when Charles married Sarah's sister?

In 1980, Charles met Sarah's younger sister Diana again, and this time she looked like a promising prospect for a royal marriage – which took place the following year. When the engagement was announced, Sarah said: "I introduced them. I'm Cupid."

For her part, Sarah has been married to Neil Edmund McCorquodale since 1980, and her married name is Lady Sarah McCorquodale. Some have written that the sister's relationship was strained, because Charles chose Diana over Sarah; others have written that the sisters were incredibly close.

The Crown is available on Netflix now. Looking for something else to watch? Check out our guide to the best TV series on Netflix and best movies on Netflix, or visit our TV Guide.