Earl Spencer compares media treatment of Harry and Meghan to Princess Diana

Earl Spencer's interview with the BBC was his first since the Palace issued a strongly worded response to his claims about King Charles.

That statement said the King was "mindful that the pain of fraternal grief can cloud reason, affect judgement and colour memory in ways others do not recognise, even many years after such a loss".

Earl Spencer, in comments first reported on Friday, reacted to it by saying: "Well, is he furious? Is he furious or is he embarrassed?"

He added: "I've only ever had two calls on the line with Prince Charles at any stage of my life.

"I was hyper alert to what he was saying and those are precisely the words that he said and I promise that to you now. Genuinely, that is what he said. I don't hear him saying he didn't say that."

Pressed on whether he had evidence to back up the claim, he said he told family and friends at the time what had been said "because it was so monstrous".

In his response to the Palace disputing his account, Earl Spencer, who shares his first name with the King, said: "They've sort of smudged that one, haven't they? They've said that recollections may vary."

When asked which Charles the public was meant to believe, he said: "I'm telling the truth."

Speaking to the Mail on Sunday, Earl Spencer accused the King of psychological manipulation over the palace's statement.

"It is not every day you wake up to find you've been gaslit by the King," he said. "It was astonishingly provocative and below the belt because it was essentially trying to say I'd lied without the King being able to deny what I'd said".

Journalist Richard Kay, who had been close friends with Diana, also wrote in the newspaper on Sunday that in the week between her death and funeral, Earl Spencer had told him of a "furious row" with Charles.

"It was 'about the boys', but he was reluctant to go further," said Kay, adding that Earl Spencer said the then prince had been "utterly pathetic".

However, speaking to BBC Radio 4's Broadcasting House on Sunday, Dame Julia Cleverdon, a trusted aide and friend of the King, said the claims about his response to Diana's death did not reflect "the language or the behaviours of a man I've known for 40 years".

Earl Spencer's book, Swan Song: Diana, My Sister, is due to be published next week and is expected to be highly critical of the Royal Family.

In further extracts published on Thursday, he claimed how the King "sounded giddily elated" when he called him after Diana's death, alleging Charles sounded like a "lottery winner".

Dame Julia said: "To say that the Prince of Wales was elated and somehow took any pleasure... he was as if a 10-tonne truck had fallen on him.

Her own husband had died a fortnight before Diana and she said Charles "could not have been more supportive, loving, concerned about the children and interested".