A slanging match doesn't usually do either side much good. Unless you're selling books, when a controversy can be extremely helpful.
Earl Spencer's book about his sister, Diana, has had six days of public accusations and counter-claims, with extensive news coverage.
So perhaps it's not surprising that even before it's officially published, Swan Song: Diana, My Sister is racing up the Amazon best-seller chart.
It's likely to be the most significant royal book since Prince Harry's startling 2023 memoir, Spare, and Andrew Lownie's 2025 book Entitled, which doomed Andrew Mountbatten-Windsor's reputation.
The coverage has been driven by a simple question: should we believe Earl Spencer's claims about the King's callousness after Diana's death? Or should we believe the unusually robust denial from Buckingham Palace?
But when you read further through the book, there's a more complicated story being told.
Earl Spencer is the brother watching events unfolding in the strange and ultimately doomed life of his sister, who has stepped from being his childhood companion to become one of the most famous women in the world.
He describes a kind of grief and irritation as Diana becomes public property and then royal property, which irks him even more, disliking the "nonsense of fawning" around the monarchy.
It's a stark reminder that Diana was only just 20 years old when she married - becoming a global superstar - and was dead 16 years later.
Earl Spencer depicts her as a caring, generous character who was haunted by self-doubt, dogged by eating disorders, lacking in warmth from her new royal family and then ultimately dragged down by the tabloid media.
"She craved acceptance, admiration, kindness, and - perhaps above all - love," writes Charles Spencer about Diana.
"She got stuck into gritty, controversial, but crucial causes partly because she had a fine, natural social conscience, but also to assuage nagging feelings of worthlessness."
And with a memoir like this it will be the extra details that will fascinate people.
The stepmother to Diana and Charles, Raine Spencer, is painted in an unflattering light, and Diana is described as getting so angry once that she pushed Raine down the staircase at their home in Althorp. "Raine fortunately landed flush on her buttocks, rather than on bone, and got up, leaving the saloon without a backwards glance," he writes. It was in response, says the book, to Raine telling Diana: "I have always felt so very sorry for the Prince of Wales, marrying someone quite as stupid as you."
There's not a single mention of Meghan, the Duchess of Sussex, even though she was talked about in the TV interviews
We're told that a "nephew" wanted Earl Spencer to be in a documentary about Diana, which will raise speculation about Prince Harry's plans for his mother's 30th anniversary next year
The book recounts that she disliked Dodi Fayed's father, Mohammed Fayed, accusing him of crudely groping her
Diana's preferences included the soap opera Crossroads and the music of David Bowie. She'd watched The Sound of Music 16 times and the paper she read was the Daily Mail
Earl Spencer will ultimately be remembered by the passionate eulogy he delivered at Diana's funeral in Westminster Abbey.
He reveals how he had pretended to have lost his copy of his speech at the rehearsal, so no one could hear it in advance and try to tone down his stinging criticism of the press and the royals.
After the hounding of Diana by the paparazzi, he says he personally rang tabloid newspaper editors to disinvite them from the Abbey funeral, after their invitations had already been sent out.
She was buried on an island in the Spencers' Althorp estate, rather than a graveyard - and the book describes how a bishop was brought to consecrate the ground to make it possible.
Much of the interest in this book has been driven by its settling of old scores with the Royal Family. It can feel like medieval barons jousting.
References to King Charles are almost all negative, including the suggestion that he was jealous of his wife's public popularity.
The book reports a conversation in which it's claimed the then-Prince Charles complained: "I mean, I'm 43,' he said, 'and I employ fifty people' – he was flushed in the face now – 'but my parents insist on treating me like – like a child!'"
The King is portrayed as resentful, with a "senior courtier" reporting an alleged comment by the late Queen: "He even resented it when I taught him the alphabet."
There's a bizarre account of discussions in the Royal Family about whether the then-Prince Charles's ears should have been pinned back.
And there's the allegation that Diana had said the King was in love with his valet, which the author himself says seemed improbable.
What comes across is how close the Spencers were to the royals - but without being friends.
Charles and Diana Spencer went to the same children's parties as the young royals.
The royals are depicted as the type of children who come round, break your toys and then disappear, in what might be an extended metaphor for how he saw Diana's story.
There's also a story about a teenage Prince Andrew smirking in a church service because the priest used the word "womb".
While the TV interviews have sought Spencer's views on Prince Harry and Prince William, the book doesn't go there.
Earl Spencer describes his opposition to the boys having to walk behind the coffin at their mother's funeral - and he talks of "how tiny, and slight, and bereft, Harry looked".
But the focus of this book is much more about the Diana era - and an elegy to the lost world of their childhood.
Earl Spencer emphasises its country house happiness, with dens, dogs and horses, but it's also dotted with cruelty, with violent nannies and the "mindless and often destructive" tradition of boarding schools.
A boy who accidentally shot and killed his father gets the mawkish nickname "Baghdad".
Although the book is about Diana, it's also about its author, the younger brother trying to make sense of what's happened - and also, like many younger brothers, being able to criticise without being able to take responsibility.
Earl Spencer talks about how little he cares for "archaic" titles for the aristocracy or royals.
And in this book, the title that seems really to have shaped his life most is "Diana's brother".
Swan Song: Diana, My Sister, by Charles Spencer. Published by Penguin.
