A new book by Charles Spencer, the late Princess Diana's brother, has triggered a public war of words with King Charles III, drawing a strongly-worded response from Buckingham Palace.

The memoir, which centers on Spencer's sister, contains damning allegations about the King. Buckingham Palace broke with its customary silence on such publications to issue an unusually direct rebuttal.

Spencer, the 9th Earl Spencer, has long acted as a guardian of his sister's memory. He delivered the address at Diana's funeral in Westminster Abbey in 1997, and has since written and spoken publicly about her life and the treatment she received from the royal family and the press.

The Palace statement marks a rare escalation. Royal households typically decline to comment on books about family members, making the force of this response a measure of how seriously officials view the claims.

No legal action has been announced. Whether the dispute moves beyond statements, or prompts a fuller reply from the King himself, will shape how this episode registers in the broader record of Charles III's reign.