King Charles has reportedly made ‘various threats’ to his son Harry and his wife Meghan Markle and is even prepared to strip them of their titles ahead of the prince’s book being released in January.

Royal author Tom Bower has revealed Harry's upcoming book Spare has strained relationships withing the Royal Family.

He said: “He has made various threats to Meghan and Harry and warned that them if they go ahead they will find themselves ostracised in a way they cannot believe. And so they are worried. First of all, I do not think their children will get titles if they go ahead and slander the Royal Family.

“But they have also got to consider their own titles, the Duke and Duchess of Sussex, could be taken away by Charles if they misbehave. That is something Meghan and Harry are very worried about because after all although she pours dirt on the royal family the whole time, whenever she introduces herself she says: ‘I am Meghan, Duchess Of Sussex.’”

Mr Bower added that the couple, who left their roles as working royals to live in the US, left the Queen’s funeral “as angry as ever” after being excluded from various events.

“In the end, they left Britain after the Queen's funeral feeling as angry as ever, if not more,” he said.

“Because they had been excluded from various events especially a reception for the heads of states, (Harry) not been allowed to wear his uniform and there was no reconciliation between them and Kate and William.

“The Sussexes released a photo of themselves to media, hours after The King unveiled his snaps with William and Kate. This was the resumption of hostilities from Montecito to the Royal Family. Meghan is a fighter, and she is fighting again now.”

Speaking of Harry he said: “Harry is brainwashed, would be the politest way of saying it, into going along with it. He thinks he has been badly treated. But there is no doubt they are a great threat to the Royal family. Harry is a very complicated, depressed, unintelligent man who is seeking a role and has really has nobody on whom he could rely, which in the end is where Meghan stepped in. A needy man met a woman who helped him with his needs.

"Anyone that gets in her way with her is ghosted and attacked. Harry has become hypersensitive, and hates the media but seeks approval from the media by going on Netflix, Spotify or Apple TV. The contradiction is enormous. They needed money, fame and to be able to tell their story on their terms.

“And what has changed is that in their trips to Britain they suddenly realised that they are going to lose their reputations. They have been given an ultimatum. Netflix is a great problem because Netflix reflects what is in Harry’s autobiography which has been ghosted (ghostwritten) for him. I am sure it contains a lot of very damaging material about Charles, William, Kate and of course against Camilla.”