Prince Philip had a library of books on UFOs. Prince Charles read Harry Potter to Prince George and Princess Charlotte, even going so far as to do the voices.
Kate, the Duchess of Cambridge, likes a bestseller – she once said during an official engagement she'd read The Girl On The Train and has been seen leaving a London bookshop with a copy of The Guernsey Literary And Potato Peel Pie Society.
But if there is one tome that won't be making its way to palace shelves, it's Prince Harry's newly revealed, as yet untitled, autobiography, set to be released next year.
Early on Tuesday, the world was treated to the latest in an increasingly long line of self-aggrandising press releases concerning the Duke and Duchess of Sussex's commercial ventures.
The Duke, it turns out, is hard at work on a memoir which "will offer an honest and captivating personal portrait, one that shows readers that behind everything they think they know lies an inspiring, courageous and uplifting human story". (Who needs Malala to inspire us when we have Harry, right?)
"I'm writing this not as the Prince I was born but as the man I have become," Harry said in a statement, triggering such a global wave of eye-rolling that medical intervention may very well be needed.
It would be very, very tempting here to point out that the man Harry has become is a WFH father-of-two; an untried, wannabe TV producer who enjoys riding his bike and reading the works of Brene Brown, and who has only ever (previously) been employed by the British state.
If Random House is giving out book deals to blokes with this calibre of credentials then every other Deadmau5-loving, late 30-somethings with family issues are in with a shot too!
But there is a much bigger learning here, to co-opt some California-lite lingo, which is that the announcement of this book equates to the starting gun being fired on a new and brutal chapter in the Sussex vs Palace civil war.
Look back over the last 30 years of royal life and you will see there have been occasional incidents of members of the royal house going rogue in the most embarrassing public fashion. Most famously Charles went on the telly to self-flagellatingly reveal he had committed adultery, after which Diana had her turn, the Bambi-eyed Princess naively laying her toxic marriage bare for TV audiences.
Critically, these interviews were both one-offs, the equivalent of pressure valves being released. They might have been deeply embarrassing to the palace, but they were seemingly driven by a deep-seated need for catharsis.
For a while there, it was possible that Harry and Meghan's Oprah interview fitted this same paradigm. Angry, hurt and with a burning need for the world to understand what had driven them to walk away from the palace, they unburdened themselves for hours in front of TV cameras in a sort of postmodern, mass-media purging.
It looked like there was the possibility that, once they'd gotten everything off their designer-clad chests, they would feel a tad better. They could toast their success with a green juice and then get stuck into making the earnestly dull content they have committed to for their corporate lords and masters, Netflix and Spotify.
Today's book news dashes any hope that this might come to pass and only confirms that all of their "truth-telling" verbiage of the last few months is only a taste of what lies ahead.
What we can now see clearly is that speaking to Oprah was the opening salvo in what is shaping up to be a drawn-out battle between the royal house and the Sussexes.
It is hardly a surprise, given the climate, that Harry allegedly hadn't told his father about his book, with news of the project having "surprised" Charles.
"No one knew," a royal insider told the New York Post, saying there had been "chaos" when the news broke.
"Oh gosh," one royal aide simply reacted when asked by the Times.
Advantage Team Sussex.
But here's the thing: Harry and Meghan might be limbering up and getting ready to keep the pressure on the palace, but the Firm has a few moves up their bespoke sleeves too. Events over the last six weeks would suggest they are a more tenacious opponent than people might realise.
If there is one thing we have seen over the last 18 months, ever since Harry and Meghan hit "send" on their history-making royal resignation, it is that both sides here seem to have no intention of backing down.
For example, in June, the Times serialised extracts from the updated edition of Robert Lacey's Battle of Brothers that raised a series of extraordinary claims about the Sussexes, including that Prince William had taken the extreme step of separating the couples' households (aka their office and staff which they had shared up until that point) and "threw Harry out" after finding out about bullying allegations made about Meghan. (The Duchess has strenuously denied the claims.)
The stories included a number of deeply negative renderings of the Sussexes, including one Kensington Palace staffer labelling her "a complete narcissist"; a courtier recounting hearing Harry "screaming and screaming down the phone"; and that William "wished to be separated from Meghan on a day-to-day basis".
It is impossible to imagine how all of this information would have come out if royal insiders had not acquiesced to (or even wanted) such damaging revelations about Harry and Meghan entering the news bloodstream.
Ditto the fact that Clarence House showed no compunction in challenging Harry's declarations that his father had "cut him off" when the Sussexes skipped town for California. Days after the interview, a friend of Charles told the Times of that money claim, "What f***ing hypocrisy. When Harry and Meghan left last year, they wanted to become 'financially independent'."
The same month, an official spokesperson told journalists that Charles had "allocated a substantial sum" to his son and daughter-in-law, providing financial support up until the northern summer of 2020.
Then came the birth of Harry and Meghan's second child, a little girl, and the melee over whether they had asked Her Majesty's permission to co-opt her lifelong nickname for their daughter. Tellingly, Buckingham Palace refused to deny a report that the Sussexes had not sought his grandmother's blessing. (Lawyers for the couple called the BBC story "false and defamatory".)
Following that kerfuffle, also in June, the Mail on Sunday reported that the Queen had (in the Mail's words), "instructed courtiers to correct any statements which misrepresent her private conversations or those of other senior royals".
"Sources say the Queen's more robust response to the tsunami of media briefings from allies of the Sussexes will go beyond the Lilibet story."
(Gosh, without the 95-year-old undertaking her usual strenuous roster of horsey events because of Covid, stuff really gets done around the palace, doesn't it?)
Taken together, these moments paint a picture of the Palace pushing back with greater regularity and assertiveness against Team Sussex than we have seen previously.
What's also worth noting is that the timing of this book news has the potential to raise hackles.
Thursday is Prince George's birthday (he's turning 8), an event perennially preceded by Kensington Palace releasing new images of the little boy. Deciding to trumpet this book deal so close to such a red-letter day in the royal calendar is … interesting, shall we say.
Then there is the Queen's Platinum Jubilee year, with vast public celebrations planned, including a four-day bank holiday long weekend and a pageant involving 5000 participants from across the UK and the Commonwealth. (Clearly they have not erred on the side of keeping things simple.)
It is meant to be a chance to restore the nation's spirits and add a bit of lustre to the royal image after a rocky few years. Now the book, and the possibility of a new swath of highly damaging royal revelations coming in 2022, will hang over the event like a sword of Damocles for the family, lending a certain ominous hue to proceedings.
If it feels like we've been here before, we have. Time and again the Sussexes do or say something that cranks up the stakes and that dramatically turns up the dial. Time and again over the last 18 months since Megxit, we have been left to come to grips with the new royal normal only for that to become replaced with an even more extraordinary, inflamed situation.
To borrow from Greek philosopher Heraclitus and the insipid inspirational quotes that clog Instagram, the only constant is change.
And for the Queen and co, the only constant in the near future is the knowledge that the worst might be yet to come.
• Daniela Elser is a royal expert and a writer with more than 15 years' experience working with a number of Australia's leading media titles.