Royal books. Where do they come from and what the hell are they for? Somewhat to my surprise, in recent years I’ve enjoyed several serious biographies of regal personages, the best of these being Jane Ridley’s Bertie: A Life of Edward VII, a story of sex, sulking and 12-course dinners. I’ve also, on occasion, been known to gobble up the kind of high-class insider gossip favoured by Tina Brown, the former editor of Vanity Fair (you’d have to be half dead not to enjoy bits of The Palace Papers). But until now, I’ve never tried out the kind of book that seems only to get published at all for the serialisation that will inevitably follow in the Daily Mail.

As experiences go, this has been quite horrifying; beneath my own coronet, my hair is now, I believe, just a little whiter. A terrible swot when it comes to writing, it’s genuinely shocking to me that Angela Levin’s Camilla: From Outcast to Future Queen Consort has made it to hard covers and not only because it’s already out of date, having been written before the Queen’s death (Levin’s publisher evidently decided not to pulp existing copies, the better that she might add an afterword). Look at its author’s acknowledgments – there is, of course, no bibliography – and in a glance, you’ll grasp its threadbare nature. Where Brown might have spoken to at least 50 courtiers and other top sneaks, Levin has simply chatted to half a dozen of Camilla’s most devoted fans. These include – cue my best Uriah Heep impression – the historian Andrew Roberts, the TV presenter Clare Balding and Craig Revel Horwood of Strictly Come Dancing fame, who once did the cha-cha-cha with her. (“He knows he is not a constitutional expert, but… ” Levin writes, by way of introduction.)

Without exception, all of them talk platitudinous rubbish, though even they are put in the shade by the novelist and arch creep Susan Hill, who believes Camilla to be a good female role model not because of what she has done, but because of what she hasn’t. (“She hasn’t been someone who had… gone into business, became head of a company and worked 24/7… she was an army wife… She hunted, rode horses, and had her friends, but she wasn’t that kind of glass-ceiling breaker.”) But hey, let us not nitpick. Our future queen is, it turns out, a tradition-buster in other ways. When, for instance, she married Charles in the Ascot Room of the Windsor Guildhall in 2005, her LK Bennett pumps rested not on marble or silk, but on a stained brown carpet. Additionally, she has been known to put lemon curd or even Nutella in her Victoria sponge cakes. (“Her delicious-looking Victoria Sponge, also known as the Victoria Sandwich Cake, was named after Queen Victoria, her husband’s great-great-great-grandmother,” Levin informs us, in ever hotter pursuit of her word count.)

Camilla Parker Bowles left school with one O-level and was sacked after only a week in her first job at Colefax and Fowler, purveyors of posh wallpaper. But these things hardly mattered. Having inherited a tidy sum from a relative, she was soon married to the soldier Andrew Parker Bowles, a situation – I’m choosing my words carefully – that persisted until 1995, at which point, newly divorced, she holed up in her bolthole Ray Mill House, which is just 10 minutes’ drive from Highgrove, the home of the man she’d loved (whatever love is) since 1970. Although it was hard, being trailed by photographers every time she popped to Sainsbury’s, Camilla is – Levin’s sources all agree – stoical to a fault. I mean, she once invited that heinous royal hater Hilary Mantel to a party at Clarence House! (According to Levin, clearly no fan of the author of Wolf Hall, partygoers were struck by the writer’s resemblance to Queen Victoria.)

Again and again, Levin repeats herself: Camilla is a good sort, so sincere and hard working; ever-radiant in her Bruce Oldfield gowns. No, it isn’t always easy being stepmother to William and Harry; Prince Andrew and Princess Anne gave her the brush-off at first; and someone called Lord Powis refused to let her spend the night in his castle. And yes, there was a bit of local difficulty with mardy-pants Meghan (though Camilla definitely did not call her a minx). However, she endured, taking refuge in simple pleasures, which for her are (or were) reading and cubbing (the training of young foxhounds to kill fox cubs). She did so because she loves her husband deeply. She is yin to his yang (or something: basically, she’s messier than him).

It may indeed be weird to hear one’s children address their stepfather as Sir (though her biographer doesn’t comment), but never mind. Straining to find the words to capture Camilla’s marital bliss, Levin concludes by noting that it must be quite something to be married to a man who doesn’t have to worry “about paying the London congestion charge… [or] sorting out issues with his computer”. Forget the coronation! Shrug off the tedium of the state opening of parliament and any number of charity concerts! When Charles’s hard drive goes haywire, it’s all taken care of at the ring of a bell.

• Camilla, Duchess of Cornwall: From Outcast to Future Queen Consort by Angela Levin is published by Simon & Schuster (£20). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply