I can think of few artists who benefit as much from overexposure as René Magritte. This was, in a sense, bound to be. A poster of The Son of Man (1964) or Golconda (1953) was de rigueur for the school study wall of any fifteen-year-old of my generation with distant claims to sensitivity, a mark of difference from the hearties on either side, with their tennis-player-scratching-her-bottom posters. The oddity and graphic crispness of Magritte’s work made for a winning combination, his bowler-hatted hommes moyens sensuels raining like so many male Mary Poppinses from an all too clearly Belgian sky.

The instant recognisability of Magritte’s work has its roots not in his training at the Académie Royale des Beaux-Arts in Brussels from 1916 to 1918 but in his postwar work as a draughtsman in the city from 1922 to 1926. During this time he made artworks for advertising companies and designed wallpaper and posters. The skills garnered from the first two of these are immediately evident in Golconda, now in the Menil Collection in Houston, Texas. The bowler-hatted men, part Thomson and Thompson, part Gilbert and George, are as obviously Magritte’s logo as the part-eaten apple is that of a certain American computer giant. His eye for pattern was also acute. Golconda would make lovely wallpaper, and no doubt has.

The Menil’s Golconda is an anomaly in being unique, hand-made and identifiable – an autograph work. It is the millions of mass-printed posters of the picture that are arguably the real Golconda, banal and yet everywhere, like the little grey men they depict. The more exposed Magritte is, in other words, the more Magritte-like he becomes. Alex Danchev’s Magritte, the final chapter of which was written by Sarah Whitfield after Danchev’s early death in 2016, opens with a claim that seems designed to be disagreed with: ‘René Magritte is the single most significant purveyor of images to the modern world.’ In terms of recognisability, Magritte is almost certainly trumped by Andy Warhol, but then the interests in ubiquity of the two men were quite different. Danchev was a researcher of ferocious meticulousness, and his book is full of plums such as this, from an unscripted radio interview given by Magritte in the 1950s: ‘Everything we see hides another thing, we always want to see what is hidden by what we see. There is … a sort of conflict, one might say, between the visible that is hidden and the visible that is apparent.’

Since Danchev sees Magritte’s defiant clarity as an ever-deepening form of disguise, two questions arise: what is he hiding and why? The response of biographers, from James Thrall Soby and David Sylvester in the 1960s to Abraham Marie Hammacher in the 1980s, has been to look to Freud for an explanation – a forgivable response given the oneiric quality of Magritte’s work. Danchev’s approach to these questions is more open-ended. He presents the facts as he doggedly finds them, leaving his audience to make the connections between Magritte’s biography and art; to each reader, his own little bowler-hatted man.

Much in Magritte’s life is precisely as you would imagine it from his work, and much precisely as you would not. Born in 1898 in small-town Lessines to a newly prosperous father, Léopold, an inspector of margarine factories, and Régina, an ex-milliner, young René’s life was as dull and as hidden as that of his little grey men. For all his outward airs and graces, Léopold was a serial philanderer and sometime syphilitic. Régina, despairing of his infidelities, drowned herself in the River Sambre when René, her oldest son, was thirteen.

Legend has long had it that Magritte was present when his mother’s body was dragged from the water three weeks later, and that her nightdress was over her face when it was – the supposed source of such images as The Lovers I and The Lovers II, of figures with their heads wrapped in scarves. Danchev quietly lays these myths to rest. The particularities of the discovery of Régina’s body seem to have been embellished, if not invented, by Magritte himself, and certainly spread by him, fiction being another form of concealment.

Thus we get to Magritte’s most famous picture, La trahison des images (‘The Treachery of Images’), with its legend Ceci n’est pas une pipe (‘This is not a pipe’) below what is clearly a pipe. It is a compelling image, not least because pipes are so dull, paired immemorially with carpet slippers and armchairs. Like all of Magritte’s works, La trahison des images is a Cretan paradox, an insolubilium. It is telling a palpable lie, and yet it is true. The work is not a pipe, but the picture of a pipe: paint on canvas. The inescapable dishonesty of art had troubled, among others, Jean-Jacques Rousseau, who had sought a way out of it with his tell-all Confessions. Perhaps it is in the same spirit that we should approach Magritte’s work, the confession here being always the same: that Magritte is not to be trusted.

And he wasn’t. As Danchev shows, the boy from Lessines was a bit of a shit. This was also one of his favoured materials for practical jokery: take, for example, the side-splitting time he poured yeast down the lavatories of a local restaurant so that its septic tank effervesced over the patrons’ shoes. Sausages, too, might be a source of hilarity. In the midst of Great War hunger in Belgium, Magritte would use his lavish allowance to buy four metres of saveloys, which he would wear down his trouser leg so that they dragged in the dust behind him. Among the observers of this was a classmate at the Académie who would shortly be diagnosed with malnutrition. It was all very Bullingdon Club. The young Magritte was also, in his own telling, a rapist. Danchev retails all of this with the stony face of one whose job it is to report rather than judge.

There is a plea in mitigation: Magritte was, perhaps, a little mad. This is where dullness came in, as well as Belgium, the two being inseparable in the painter’s mind. In Danchev’s account, boredom was not a thing forced on Magritte but one he actively courted. For a quarter of a century, from 1930 to 1954, he lived in the same dingy flat in a drab part of Brussels that now houses the Musée René Magritte. Dullness was a safe haven, a place free of devils. Here he could by turns abuse his beautiful wife, Georgette, and spoil her rotten, cooking her excellent meals and walking their dogs while she lay on the sofa and dozed. As always, there were two Magrittes, the seen and the unseen. Many of his best-known works – Empire of Light, Personal Values – date from this time of fecund aridity.

This is a fine book, and Whitfield’s tenth chapter, covering the last twenty years of its subject’s life, does Danchev’s efforts full justice. As a historian, Danchev was polymathic, writing on everything from artists’ manifestos and Lord Alanbrooke to the Gulf War and Braque. If there is a single annoyance in Magritte: A Life, it is Danchev’s tendency to wear his breadth of knowledge on his sleeve: quoting Félix Fénéon, Humpty Dumpty and Samuel Beckett on successive pages looks like showing off. But this is a quibble. For those who love Magritte and those who do not, Danchev’s biography will come as a revelation.