Writing in May's issue of Saga Magazine, broadcaster Gyles Brandreth shares previously unknown details about Charles's relationship with William and Harry, and the unusual way he would communicate with his sons.
Mr Brandreth said that the King is a big fan of Radio 4's Just A Minute comedy panel game, which began in 1967 and was hosted for more than 50 years by Nicholas Parsons.
"In fact, he told me he used to leave voicemail messages for William and Harry in the style of Just a Minute, doing his best to say what he had to say in under 60 seconds, without hesitation, deviation or repetition," Mr Brandreth writes.
Of Charles and his wife of 18 years, Camilla, he added: "The pair of them share a marvellous sense of humour. It's such good news that we have this double act, who so clearly get on."
The King will be joined by immediate members of his family as he is crowned at Westminster Abbey on Saturday. Here's everything we know about the service so far...
Prince George has a starring role as one of his grandfather's pages of honour, along with three of the Queen Consort's grandsons, Gus and Louis Lopes, and Freddy Parker Bowles.
Meanwhile, the Duke of Sussex will be flying over from the US to be reunited with his family for the first time since the release of his explosive Netflix docuseries last December and tell-all memoir, Spare, published in January.
Harry's controversial autobiography includes claims his brother William physically attacked him and that the King put his own interests above Harry's, and was jealous of the Duchess of Sussex and the Princess of Wales.
The Duke also said in an interview that his stepmother Camilla was a "villain" and "dangerous", accusing her of rehabilitating her image at the expense of his.
Harry, in his interview with Oprah Winfrey in 2021, said Charles stopped taking his calls when he was trying to discuss stepping down as a working royal in 2019.
"My father and my brother, they are trapped. They don't get to leave. And I have huge compassion for that," Harry told the US chat show host.
The coronation will mark the first time the Duke will be reunited with his family since the late Queen Elizabeth II's state funeral last September.
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