King Charles urged Princes William and Harry not to “make (his) final years a misery”.

The 74-year-old monarch, who took the throne in September 2022 after his late mother Queen Elizabeth died, spoke to both his feuding sons following the funeral of his father Prince Philip at St George’s Chapel at Windsor Castle in April 2021 and called on them to put their differences aside.

In a leaked extract from his upcoming memoir ‘Spare’ obtained by The Guardian newspaper’s US website, Harry, 38, recounted an anguished meeting with his father and older brother Prince William, 40, and told how the king stood between his sons “looking up at our flushed faces”.

He quoted the king as saying: “Please, boys. Don’t make my final years a misery.”

Harry’s book’s title refers to his nickname as ‘the spare heir’ to William, and early in his book he claims his father said to his then-wife Princess Diana on the day he was born: “Wonderful! Now you’ve given me an heir and a spare – my work is done.”

The book is also said to see Harry accuse William of physically attacking him at his home in Windsor in 2019 after his brother allegedly branded his wife Meghan, Duchess of Sussex, “difficult”, “rude” and “abrasive”.

The duke then claims the row escalated and William - who he called Willy in the anecdote - “grabbed me by the collar, ripping my necklace, and... knocked me to the floor”.

Harry says he had given his brother a glass of water during the bust up and had said: “I can’t speak to you when you’re like this."

He added: "He set down the water, called me another name, then came at me. It all happened so fast. So very fast. He grabbed me by the collar, ripping my necklace, and he knocked me to the floor.

“I landed on the dog’s bowl, which cracked under my back, the pieces cutting into me. I lay there for a moment, dazed, then got to my feet and told him to get out.”

Harry also claims William told him: “You don’t need to tell Meg about this,” and he is said to have replied: “You mean that you attacked me?”

The duke writes that William then said: “I didn’t attack you, Harold.”

Harry also claims Meghan, 41, with whom he shares son Archie, three, and 19-month-old daughter Lilibet, later spotted “scrapes and bruises”, and was “terribly sad” about the alleged altercation.