Like making barrels or thatching roofs, writing about the royal family is one of the traditional craft skills of this country. It involves raking over yellowing newspaper cuttings and polishing old chestnuts about “majesty” and “radiance”. But books about the royals sell, including a recent clutch of glum ones, some ostensibly written by members of the family themselves, so they keep on coming. Just when you think you can’t face another one, a book appears that makes you wonder if you’ve ever read a proper account of the queen and her relations before. Paradoxically, it has taken a humorist, Craig Brown of the Daily Mail and Private Eye, a man who supposedly trades in throwaway wisecracks, to tell us something thought-provoking, perhaps even deep, about monarchy.

But before I praise him for what he’s written about the queen, I have to praise him for what he’s read about her first. He appears to have worked his way single-handedly through every book about Elizabeth II ever published, a phrase that very much begs the payoff: “So you don’t have to.” From The Little Princesses: The Intimate Story of HRH Princess Elizabeth and HRH Princess Margaret right the way through to Spare by Prince Harry, Brown has digested them all. It’s the sort of feat that might once have been witnessed in the ancient library of Alexandria, except that instead of poring over papyrus scrolls about gods and heroes, Brown has immersed himself in the life of a latter-day legend, as the queen appeared to her simpering chroniclers. He compares the experience to “wading through candyfloss: you emerge pink and queasy, but also undernourished”.

It’s a tough job, but somebody’s got to do it – and I mean that sincerely, because Brown has done us all a favour with his flamingo-coloured odyssey. The memoirs of courtiers, flunkies and hangers-on are among his primary sources, but his research extends to royal encounters recalled by politicians and celebrities. It’s biography by crowdsourcing, you might say. It follows Brown’s similar books about Princess Margaret and the Beatles, completing a triptych of 20th-century British portraits. The author is a snapper-up of unconsidered trifles and these end up furnishing a vivid and remarkably telling study of our late head of state, and even more so of the people she reigned over for 70 years.

In 112 often short chapters, the many enjoyable vignettes include the efforts of the go-getting Labour minister Tony Benn to strike a blow for modern Britain by removing the queen’s head from postage stamps. These don’t quite climax with Benn’s own head on a pikestaff, but the queen and her advisers silkily outmanoeuvre him. When Benn is promoted from postmaster general to minister of technology, he goes to be sworn in and she tells him: “I’m sure you’ll miss your stamps.” We already knew that she loved corgis, but perhaps not that she kept a plate of doggie treats on the table at Windsor Castle. The former cabinet minister Alan Johnson told a colleague how much he had enjoyed the cheeseboard there, in particular “the unusual dark biscuits”: Brown says the queen’s “naughty streak got the better of her”. He is even interested in simulacra of the sovereign – her lookalikes and waxwork effigies – and goes to an auction of royal ephemera.

On the book jacket, a portrait of Elizabeth is encircled by the letter “Q” in the form of a giant drop cap: it stands for her title, of course, but it also seems to put her at the centre of a great riddle. Brown doesn’t dissent from the widely held view that the queen was sphinxlike. If this is a potential disappointment to readers, it’s not one the author shares. He doesn’t treat the enigma of the queen as a dead end; on the contrary, it’s what interests him most about her – a blank that he’s eager to fill in. When people look at her, they’re really looking in the mirror or at the bottom of a well, he says, even at “the boatman to their subconscious”.

His spoof diaries of the famous in Private Eye (“as told to Craig Brown”) lampoon the cast-iron self-absorption of his targets and he makes a plausible case that the stories people tell of their brushes with the late ruler say more about them than they do about her. “Like the Mona Lisa, the queen brought out the solipsist in everyone: however many there were in a room, each person felt her eyes catching theirs, her thoughts turning towards them.” Few emerge from meeting her able to recall anything she said. Even the most self-assured can be fazed, while the queen herself, with a lot of flesh to press and a lifetime of diplomatic experience, keeps the conversation brief and light.

Her comments might seem unremarkable, but Brown is ready to discern gnomic meaning in them. She asks the novelist Sybille Bedford: “How long have you been writing?” and when the reply comes back: “All my life,” the queen says: “Oh dear! Oh well.” Brown adds: “With those four words, she had in fact hit the nail on the head. Throughout her life Bedford had found the act of writing close to unbearable.”

Are the queen’s critics right that there was little more to her than met the eye, or was she in fact a master of psychological jujitsu, turning the gaze of the outside world back upon itself? Perhaps she is speaking to us between the lines of what others say about her. This might just be her story, as told to Craig Brown.