All biography is both an act of homage and a labour of dissection, and all biographers are jealous of their subjects. Most keep it cool, but some like it hot and have created a distinct category in which jealousy becomes murder followed by necromancy: the one they hug is asphyxiated — but lo! — they breathe their own air back into it. Sartre’s book on Jean Genet is such a work, as are Brigid Brophy’s on Ronald Firbank and Roger Lewis’s on Anthony Burgess.

Claude Arnaud’s on Jean Cocteau is yet another. Its approach is intensely romantic. Everyone is heaving in lurid colours. Arnaud certainly knows his material; and that he carefully references printed sources along the way is adroit, a necessity to the illusion, like the pins which hold a provisional costume together. The result is a mind-boggling excursion through Cocteau’s many milieux: from his teenage beginnings as a poet in Proustian Paris; through the Great War and the Modern movement of the 1920s in collaboration with Diaghilev, Satie, Stravinsky and Picasso; followed by the macabre uncertainties of the 1930s and later in Nazi-occupied Paris; and on to postwar film making and international celebrity. The parade of boyfriends and benefactresses is spectacular, and the near-lifelong opium addiction is paralleled by the manner in which the story moves forward in a kind of peristaltic reverie.

There are many delightful incidentals, the sort of thing biographers can easily overlook. Cocteau’s spelling was poor; he had facelifts; he couldn’t swim; he suffered from eczema; he never picked up the bill in a restaurant because he never had money (his art projects were uncommercial and he lived on handouts). There are numerous analytical hits too, along the lines of Cocteau ‘felt himself slipping into freefall when he failed to please’. Anyone interested in the cultural scene of the period will relish a feast that is both magnificent and intimate. But it needs to be qualified.

None of it is definitive. Some of it is fallacious, much of it off-balance. Arnaud’s method is Proustian, with long sentences ballooning into voluptuous paragraphs which take on the aspect of giant blisters through whose translucent walls Cocteau may be observed darting about like a guppy, a pathetic specimen, a victim of melodramatic shrinkage across 1,000 pages. Banalities can come overdressed. Arnaud’s Cocteau never laughs; he is always disappointed, with a self-esteem so low that it implies a schizophrenic divorce from reality.

Given Cocteau’s nervous temperament and gifts, his life would always be a dance of stresses; but it also had a fortunate aspect of which he was well aware. He suffered tragedies, especially the early death of Raymond Radiguet, which turned him to opium, and he was widely attacked; but in consequence his buoyancy is almost a definition of sanity and good heart. Arnaud’s recreation of the attacks — Breton’s, Picassos’s, Stravinsky’s and many others — with little corrective, leaves the impression that the attacks were justified. Thus Cocteau’s amiability and kindness are repeatedly devalued as obsequiousness and masochism. Occasionally Arnaud pitches in with his own direct slaps: ‘Cocteau, whose work still today takes up too much room in certain galleries’; or ‘the sad clown of modernity’, whose enthusiasm is snubbed as ‘limitless credulity’.

The mother is all but invisible, yet Cocteau lived with her until well into middle age. Arnaud produces an unprecedentedly full account of Cocteau’s opium addiction and there is much on the emotional aspect of his homosexuality — but prudishly, nothing on his actual sex life, and virtually nothing on his huge oeuvre of erotic drawings. And where is the voice? The question is triggered by a telling quotation from Maurice Sachs: ‘…the noise of broken windows produced by the enchanting voice of Cocteau.’ I can’t locate it within the Arnaud boom.

Arnaud’s text was published in 2003 in France, and even then presented an old-fashioned view: that Cocteau was a failure because he wasn’t the most important French writer of his time, that he was a dithering Mercutio scorned by the super-greats. I’ve always seen him quite differently. His versatility, not his writing, is the key to his originality and cultural status. He was trans-arts and trans-class, apolitical and pragmatic, improvising with whatever was to hand, Picasso one day, someone off the street the next, equally at home in the academy and in the yard.

This was exceptional then but is widespread today. He was a harbinger of the future as the progenitor of France’s New Wave cinema, as a post-modernist avant la lettre, as a man seen publicly with his various lovers (though unlike Gide, he never campaigned as a homosexual, nor ever used the word), as a man who travelled light with few possessions, as the godfather of Warholism. And like Warhol, Cocteau is generous, immediate and completely natural, the very opposite of a poseur. ‘His lack of pettiness is so rare,’ said Simone de Beauvoir.

His reach was extraordinary. In his youth he met people who’d known Balzac, who was born in the 18th century; and in his final, most wonderful film, Le Testament d’Orphée, he extends a finger towards the Beatles. This borders on timelessness. In everything he did — poet, novelist, dramatist, memoirist, illustrator, designer, director, entrepreneur, impresario, freelance journalist, night-club host, disc jockey, drug fiend, gossip, socialite, wit, frolicsome mischief-maker — he speaks to us as a contemporary. So I was happy indeed to learn that the epitaph on his gravestone reads: Je reste avec vous.