Earl Spencer has said Prince William and Prince Harry would not be surprised by his claim that King Charles once said Diana would soon be forgotten after her death. The allegation, contained in Spencer’s forthcoming memoir, has prompted an unusually strong response from the Palace, which questioned the accuracy of his recollection.

Spencer said the alleged exchange occurred during an argument about whether William and Harry, then aged 15 and 12, should walk behind their mother’s coffin in 1997. He believes his funeral eulogy, particularly its assertion that Diana’s qualities would “never be extinguished”, directly rebutted Charles’s reported remark, while denying that references to other undisclosed material about the King were intended as threats.