The book, titled 'Il Canto del Cigno - Diana, mia sorella', is due out shortly and has been previewed in extracts by the Daily Mail. Written by Charles Spencer, the 9th Earl Spencer, it reconstructs the life of the late princess from the perspective of her younger brother, nearly three decades after her death in the Alma tunnel in Paris.
Among the passages drawing attention is Spencer's account of opposing, in vain, the royal family's decision in 1997 to have Princes William and Harry, then 15 and 12, walk behind their mother's funeral cortege. Spencer says he was convinced Diana would not have wanted it.
He further writes that his objection provoked a malignant fury in Charles, then Prince of Wales and fresh from the turbulent divorce of the previous year, a reaction he describes as laced with contempt for his just-dead former wife and horror at the emotion her death stirred around the world. The book attributes to Charles the words: "Don't worry, we'll forget her soon."
Buckingham Palace moved quickly to deny the account in writing on behalf of the current 77-year-old monarch, without diplomatic softening: "His Majesty is aware that grief over the loss of a sister can cloud reason, influence judgment and alter memories." The speed and tone of the response are being described as rare.
British media have labelled the exchange a "war of words". Some commentators noted that the reply echoed Buckingham Palace's restrained 2021 statement, issued while Elizabeth II still reigned, after Prince Harry and Meghan attributed an inappropriate remark about the skin colour of their first child, Archie, to an anonymous member of the Windsor household. That statement said that "recollections may vary". The difference now, observers note, lies in the barely concealed anger of the response to Earl Spencer.
Peter Hunt, a former BBC royal correspondent, questioned whether royal staff had "lost their heads" in rushing to comment in terms that struck him as almost threatening. Other commentators more aligned with the palace public-relations operation defended the king, arguing that the traditional royal reticence summed up by the motto 'never complain, never explain' could have looked like an admission of guilt.
Those defenders have also questioned the credibility of Diana's 62-year-old brother, recalling his most talked-about past episodes and raising suspicions of commercial interest behind recollections that have surfaced only now, almost three decades after the events. Julian Payne, a former spokesman for Charles, said he did not recognise him at all in the language of the offence against the memory of the dead.
The dispute has left William and Harry, once inseparable and now at odds, publicly silent, though it forces both to reckon with past traumas from different positions. William, the heir to the throne, is necessarily aligned with his father and was on an institutional visit with Kate on the Scottish island of Bute. Harry, the rebellious younger son, returned to live in Britain with his family only weeks ago after six years of American self-exile and was carrying out a first public engagement, a charity fundraising event in London, against a backdrop of fresh tensions with the family.
A couple of months ago Harry was a guest of his uncle Charles Spencer at the ancestral home of Althorp, in whose grounds Diana lies buried in a peace that even death, the episode suggests, has not made entirely final.
The controversy also clouded a significant day for the sovereign, who was in Scotland taking part in a forum on the "existential dangers" of uncontrolled development of artificial intelligence, before an international audience of business figures and experts. The episode threatens a further shock to a monarchy already surrounded by uncertainties and scandals.