In a clip from the interview to air on Britain’s ITV, Harry speaks about being unable to show any emotion when meeting mourners following the death of his mother, Diana, Princess of Wales, in 1997.

“Everyone knows where they were and what they were doing the night my mother died,” he tells presenter Tom Bradby.

“I cried once, at the burial, and you know I go into detail about how strange it was and how actually there was some guilt that I felt, and I think William felt as well, by walking around the outside of Kensington Palace.”

Harry describes feeling the mourners’ tears on his hands when he shook them.

“There were 50,000 bouquets of flowers to our mother and there we were shaking people’s hands, smiling,” he says.

“I’ve seen the videos, right, I looked back over it all. And the wet hands that we were shaking, we couldn’t understand why their hands were wet, but it was all the tears that they were wiping away.

“Everyone thought and felt like they knew our mum, and the two closest people to her, the two most loved people by her, were unable to show any emotion in that moment.”

A string of revelations have already been leaked from the memoir, Spare, which is due to be published on Tuesday.

Harry says in the book he thinks that he is unable to cry in public because of his family’s preference for not showing emotion.

According to The Telegraph newspaper, Harry writes: “I disliked the touch of those hands. What’s more, I disliked how they made me feel: guilty.

“Why was there all that crying from people when I neither cried nor had cried?

“I wanted to cry, and I had tried, because my mother’s life had been so sad … but I couldn’t … not a drop.

“Perhaps I had learnt too well, had absorbed too thoroughly the family maxim that crying was never an option – never.”

The Telegraph also reports the book details claims of heated behind-the-scenes arguments between Diana’s brother, Earl Spencer, and the royal family about whether 12-year-old Harry and 15-year-old William should walk behind their mother’s coffin at her funeral.

The prince’s uncle “flew into a rage” at the idea, calling it “a barbarity”, Harry writes in Spare, recalling the Earl saying: “You cannot force these children to walk behind their mother’s coffin. It’s a barbarity!”

But when an alternative plan had been suggested of William following his mother’s hearse on his own, Harry said he had objected.

“It didn’t seem right that Willy would have such a hard time without me,” he says.

Harry writes in the book that “It seemed like a lot to ask for two children”, adding: “Several adults were horrified”.

The controversial book has been the subject of headlines for days as excerpts were leaked detailing personal details of Harry’s love life, drug-taking and rifts within his family.