In the latest bombshell claims from his new book, Earl Spencer says there was “a lack of obvious care” for a 12-year-old Prince Harry in the immediate aftermath of Princess Diana’s funeral.

Spencer, in excerpts from Swan Song: Diana, My Sister, said he has long wondered whether greater support at the time could have helped his nephew Harry in later life.

And he has insisted he is “telling the truth” about a claim in his book that the King told him Diana would be forgotten “soon enough” following her death. Spencer told the BBC: “Those are exactly the words he said.”

In the book, currently being serialised in the , Spencer says he was concerned about the “despair and torment” Harry suffered in the wake of his mother’s death and funeral.

Spencer adds: “I have often looked back, reckoning that a more caring hand at such points as this would have helped him enormously in the future.”

It follows claims published on Thursday that Charles had called Diana “a bit chubby”, plunging her into an eating disorder ahead of their lavish wedding.

Spencer also alleged that the then Prince of Wales “sounded giddily elated... like a lottery winner” on the night of Diana’s death.

On Wednesday, Buckingham Palace issued an unusually strong statement regarding Spencer’s claims.

A Palace spokesperson said: “While we do not comment on books as a matter of principle, His Majesty is mindful that the pain of fraternal grief can cloud reason, affect judgment and colour memory in ways others do not recognise, even many years after such a loss.”

Spencer said Buckingham Palace has not explicitly denied that the King told him “rest assured, we’ll forget her soon enough”, days after Diana’s death.

Spencer told the BBC’s Laura Kuenssberg: “They haven’t actually [denied the claims)], Laura, they’ve sort of smudged that one, haven’t they? They’ve said recollections may vary.”

Spencer alleges Harry was allowed to spin out of control

After the ordeal of the funeral, Spencer recalled the train journey to Althorp – where Diana was buried on the family estate- with the rest of the Royal Family, when he observed his younger nephew closely.

The Earl writes: “My chief memory of that train journey is of being concerned at the lack of obvious care for Harry, as he decompressed from the ghastliness of the morning.”

After the “tunnel of grief” with crowds of mourners sobbing and calling out to the two princes, Spencer claims Harry “seemed so very alone” on that journey.

“He needed Diana’s hugs, of course, and they would forever be denied him. But instead of calm and nurture, he was allowed to spin out of control.”

Spencer says he has repeatedly returned to the memory in the years since, wondering if greater support could have helped his young nephew’s development and future struggles.

“I have often looked back, reckoning that a more caring hand at such points as this would have helped him enormously in the future,” he writes. “Instead, he seemed so very alone in his despair and torment.”

Spencer: ‘Those were Charles’s exact words’

On Friday, Spencer said he was “telling the truth” about a phone call with Charles in the days after his sister’s death.

Spencer claims in a new book that the then Prince of Wales said “we’ll forget her soon enough” during an argument over whether Princes William and Harry should walk in Diana’s funeral procession.

Buckingham Palace said the King was “mindful that the pain of fraternal grief can cloud reason, affect judgment and colour memory in ways others do not recognise, even many years after such a loss”.

Spencer told the BBC: “I can tell you here and now, those are exactly the words he said.

“Well, is he furious? Is he furious or is he embarrassed?”

“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.”

Asked about Spencer’s claims in his BBC interview, and about latest revelations in his book, Buckingham Palace declined to comment and referred to Wednesday’s statement.

Procession behind Diana’s coffin ‘a form of mental torture’

Many of the claims in the book’s latest extracts concern the procession of Prince Philip, William, Harry, then Prince Charles and Spencer through Westminster for Diana’s funeral.

Spencer describes the march behind his sister’s coffin as the “most harrowing experience of my life” and says it has since returned to him in “dozens of fitful nightmares”.

He took the central position, flanked by William, 15, and Harry, 12. He said that, as the older of the two boys, William showed “greater composure and maturity”, though he imagined the teenager was “suffering equally terribly”.

His greatest concern, he writes, was for Harry, who looked “tiny, and slight, and bereft”.

Spencer recalls that he “wondered how on earth this heartbroken child could bear the ordeal of that moment, or how he could possibly be expected to deal with the agony that the day ahead would insist upon”.

When the procession briefly moved beneath a large arch, Spencer says he took a brief opportunity to comfort the grieving 12-year-old. “Relieved that nobody could see us here, I quickly leant across to Harry, and gave him an encouraging hug,” he writes. “Well done, Harry! You’re doing bloody brilliantly!”

Spencer says the waves of public grief directed towards them were so intense that the procession amounted to a “form of mental torture”.

Queen ‘wanted Diana to be buried on royal grounds’

Spencer alleges that the late Queen Elizabeth’s initial reaction to the news that Diana had been in a car crash was: “What is she up to now?”

But later, he said, she expressed a wish for the princess to be laid to rest at the royal burial ground at Frogmore, near Windsor Castle.

But the Spencers were “determined that Diana must come home to Althorp”. He also recalls refusing an offer to give Diana her HRH title back posthumously.

“The title should never have been removed during her life, in which case it would not have been necessary to offer it to her in death,” he writes.

During her burial on the island in the Round Oval lake, several mourners threw flowers on top of her coffin. “Prince Charles plucked a single stem from my bouquet for Diana and let it drop on his ex-wife’s coffin,” Spencer recalls.

“How very generous, I thought, angry now on Diana’s behalf, as she began to disappear under the soil.”

The next part of Earl Spencer’s book will be serialised by The Mail on Sunday on 20 September.

Spotlight on William and Harry

Spencer recalls the funeral at Westminster Abbey, with Diana’s sons seated so close to the coffin that “they had no privacy” with the public “devouring their every move”.

“I could not help looking repeatedly at my nephews. I felt compelled to check how they were doing, but I did not want to catch their eye in case they felt they were being judged or stared at,” he writes.

He recalls the words of his 1997 eulogy, which addressed his nephews directly: “William and Harry, we all care desperately for you today.

“We are all chewed up with sadness at the loss of a woman who was not even our mother. How great your suffering is, we cannot even imagine.”

Spencer also alleged that Princess Margaret, once an ally of Diana’s, refused to bow to her coffin when it passed by.

He claimed Margaret had considered Diana’s explosive 1995 interview “an unforgivable act of treachery against the Royal Family”.

Diana struggled to stand up for herself

Earl Spencer also recalled how his sister had opened up to him about “not wanting to rock the boat”, perhaps as a result of their parents divorce during her childhood.

This meant that later on in life “she found it hard to make complaints, or to stand up for herself”, he writes.

She once confided to him that she could not even face returning clothes that did not fit her. “I’d much rather put up with a piece of clothing that I can never wear than face upsetting the shop assistant,” Diana told him.