Earl Spencer has claimed he told US news anchor Barbara Walters the King said “we’ll forget her soon enough” in the wake of Diana, Princess of Wales’s death.

The allegation about the monarch, which features in the earl’s new book Swan Song: Diana, My Sister, has sparked a war of words with Buckingham Palace, who hit back saying “fraternal grief can cloud reason, affect judgment and colour memory”.

But the earl said on Monday: “I know I heard that… I told people at the time. I told Barbara Walters, actually, at the time.

“But they have to gaslight. They have to sort of pretend there’s something wrong with my mind or my memory. There’s nothing wrong with either.”

He also revealed the Duke of Sussex asked him after the release of the book whether there was anything that would embarrass him.

“Harry was sort of like ‘Is there anything in there that would be embarrassing to me?’. I said ‘absolutely not’. I’m very specific about people’s privacy,” the earl said.

The controversial memoir, released ahead of the 30th anniversary of Diana’s death next year, had made headlines around the world for its string of allegations against the King.

It also alleges Charles, then the Prince of Wales, “sounded giddily elated – like a lottery winner” when he spoke to the earl after the princess’s death.