Earl Spencer William and Harry Diana's Death King Charles
Earl Spencer says William and Harry already know his claims about King Charles' reaction about their mum, Princess Diana's death George Bush Presidential Library and Museum, Public domain, via Wikimedia Commons

The fallout from Princess Diana's death has resurfaced almost three decades later, with her brother Earl Spencer saying Princes William and Harry will not be surprised by his claims about King Charles.

Spencer made the comments during a BBC interview ahead of the publication of his memoir, Swan Song: Diana, My Sister, which contains his recollections of conversations with the then Prince Charles following Diana's death in 1997.

Buckingham Palace has raised questions about the reliability of Spencer's recollection, saying grief can 'cloud reason, affect judgment and colour memory'.

Earl Spencer Says William and Harry Know His Claims

Asked whether William and Harry were surprised by his account, Spencer declined to discuss private conversations with his nephews but said the claims would not be new to them.

'I don't like to talk about what I've been speaking about to William and Harry, but this will not be a surprise to them. I will tell you that these words will not be a surprise to them,' Spencer told BBC's Laura Kuenssberg.

The comments concern Spencer's account of an alleged conversation with Charles in the days after Diana's death. He claims the then Prince of Wales became angry during a disagreement about whether William and Harry, then aged 15 and 12, should walk behind their mother's coffin.

Spencer alleges Charles later told him, 'Rest assured, we'll forget her soon enough.' Buckingham Palace has not directly addressed the alleged words, but said the King was mindful that grief can 'cloud reason, affect judgment and colour memory' in ways others do not recognise.

Charles Spencer Recalls King Charles' Alleged 'Giddy Tone'

Spencer has also described his first conversation with Charles after Diana died as unsettling, claiming he detected 'a sort of giddy tone'in the then Prince of Wales's voice.

Spencer said he had received numerous calls from people who were shocked by Diana's death, but felt there was 'a lightness in his tone about Diana's death that really jarred with me' when speaking to his brother-in-law.

The account also appears in Swan Song: Diana, My Sister, which is due to be published on 22 September. The memoir is Spencer's personal account of his sister's life, her marriage to Charles and the events surrounding her death, with the Earl describing it as 'a brother's tribute to an extraordinary sister'.

'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 wrote in the book. The passage is Spencer's description of how he remembers Charles sounding during their conversation.

The book is being released as the 30th anniversary of Diana's death approaches. Spencer has said he wrote it after repeatedly receiving requests to discuss his sister and because he wanted to set down his own memories rather than rely on accounts he believes contain inaccuracies.

How Princess Diana Died in Paris

Princess Diana died on 31 August 1997 after the Mercedes carrying her, Dodi Fayed and driver Henri Paul crashed in the Pont de l'Alma tunnel in Paris shortly after midnight. Dodi and Paul died in the accident, while Diana was taken to La Pitié-Salpêtrière Hospital, where she died from her injuries after emergency surgery.

The vehicle had been travelling at high speed while being pursued by photographers. A subsequent British inquest jury found that Diana and Dodi were unlawfully killed as a result of the grossly negligent driving of Paul and the following vehicles, with alcohol affecting Paul's judgement and the failure to wear seatbelts also identified as contributing factors.

The circumstances of Diana's death generated years of speculation and conspiracy theories. British investigations found no evidence supporting claims of a conspiracy to murder her, while Diana was declared dead at 3am BST after undergoing emergency surgery in Paris.

Spencer's latest comments have placed renewed attention on the events surrounding Diana's death and the relationship between her family and the Royal Family. Further excerpts from Swan Song: Diana, My Sister have emerged ahead of its publication, including accounts of the days immediately following the fatal crash.