Earl Spencer, the brother of Diana, Princess of Wales, has claimed that King Charles, then Prince Charles, sounded "giddily elated" in a phone call following his sister's death in 1997. The allegation is detailed in a new book by Earl Spencer, titled "Swan Song: Diana, My Sister," which is set to be published next week. Buckingham Palace has issued a strong rebuttal to the claims, asserting that the pain of grief can affect judgment and memory.

The latest accusations follow earlier extracts from the memoir that purportedly revealed Charles stating of Diana: "We'll forget her soon enough." In response to these earlier claims, a Palace spokesperson stated that while they do not comment on books as a 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."

Earl Spencer recounts being alerted to the fatal car crash on August 31, 1997, by a call from his sister Jane in the early hours of the morning at his home in Cape Town, South Africa. During the subsequent calls that confirmed Diana's death, he alleges that Prince Charles telephoned him. "Unlike my other callers, who were stunned, barely able to articulate their condolences and offers of help, he sounded giddily elated - like a lottery winner, I remember thinking at the time," Spencer writes in his memoir, according to excerpts published by the Daily Mail.

Spencer further claims that Charles informed him he had told Princes William and Harry of their mother's death first thing that morning, breaking the news to them in their bedrooms at Balmoral. Diana and Charles divorced in August 1996, a year before the princess's death. The memoir is expected to delve into the late princess's troubled marriage, with Earl Spencer also claiming a friend of Diana's told him that on the eve of their wedding in July 1981, Prince Charles confessed he was "not actually in love with her."

The book's allegations are highly personal and interpret the motives of the King and the royal family in a harsh light. The primary evidence presented is Earl Spencer's recollection of conversations during a deeply emotional period nearly three decades ago. It remains to be seen how the public will react to these revelations, whether they will embrace the book as a new perspective from the Spencer family or deem such private disputes inappropriate for public airing.

Representatives for Prince Harry have stated they do not wish to comment on the book. Buckingham Palace has reiterated its earlier response, rejecting the account of Prince Charles's demeanor following Diana's death in Paris. BBC News has not yet had access to the full text of "Swan Song: Diana, My Sister."

In his memoir, Earl Spencer also touches upon his sister's marital difficulties, writing that "things became very difficult indeed in the marriage early on." He adds that he is sure "both spouses despaired of the other at times." He now believes his sister may have had attention deficit hyperactivity disorder (ADHD).

This latest controversy surrounding Princess Diana's death and the reactions of the royal family highlights the enduring public fascination with her life and the events surrounding her final days. The differing accounts from Earl Spencer and the Palace underscore the deep-seated tensions and differing recollections that can emerge in the wake of profound personal tragedy.