The Duke of Sussex’s disclosures in his new book are the sort that usually “come from B-list celebrities”, a friend of the King has said.

Broadcaster Jonathan Dimbleby, who interviewed Charles in 1994 when the then Prince of Wales admitted having an affair, said he was “perplexed” by Harry’s decision to publish a book.

The memoir, Spare, which was accidentally released early in Spain, includes personal details of his love life, drug-taking and rifts within his family.

Mr Dimbleby, 78, told BBC Radio 4’s Today programme he imagines the King, as Harry’s father, is “extremely pained” and “very frustrated” by the situation and “would be very anxious to bring it to an end”.

In 1994 Charles confessed to adultery in the televised interview with Mr Dimbleby, after his marriage had “irretrievably broken down”.

Of the book, Mr Dimbleby said: “I’m concerned incidentally that everyone uses the word ‘revelations’.

“Yes, there are obviously revelations about how he lost his virginity, taking drugs and how many people he feels he might have shot down in Afghanistan from his Apache, but those are the kinds of revelations in part that you would expect, I suppose, from a kind of B-list celebrity.

“Much more significant are not what you would call revelations but allegations – complaints, the anger and pain of what he is saying.

“His assertion that this is his side because so far there has only been one side. It seems to me that I have not heard the other side at all because the other side is always silent.”

Harry has said in promotional interviews for the memoir that he would like to reconcile with his family.

Mr Dimbleby added: “So I am perplexed.

“I genuinely can’t believe it is merely to make a great deal of money because of the perfectly natural urge to want to protect his family, his wife and his children in a very uncertain future.

“I think there is much more to that, but if he wants reconciliation, I don’t understand how you do it by, as it were metaphorically, sitting in your Apache and firing pot shots at people who are not going to fire back, as he must very well know.”

He also told the programme that Charles is possibly “deeply pained by it but he will get on with the job – that’s what they do”.

Harry has “perfectly understandably constructed a narrative of his life” which goes back to “the acute enduring distress of the loss” of his mother Diana, Princess of Wales, who died in a car crash in 1997, according to Mr Dimbleby.

He told the programme that a “wise counsellor” could have advised Harry not to go public with his feelings, if he hoped to salvage his relationship with Charles and his brother William, the Prince of Wales.

Mr Dimbleby also said he would be “very surprised” if Harry was not invited to the coronation, because to do otherwise would “simply fuel the flames”.

He added that questions over a range of issues in the royal family such as transparency, funding, and its scale and size, remain, but Mr Dimbleby did not feel it is under threat or that Charles’s reputation has been damaged.