Gallic bred: The mad life of Serge Gainsbourg

Physically, he was unprepossessing. With his prominent ears, heavy-lidded eyes and long nose, he looked, as one French commentator put it, "like a drowsy turtle". (For this, he was characteristically unapologetic: "Ugliness," he declared, "is in a way superior to beauty, because it endures.") He could play the piano and guitar, though he was far from a virtuoso; his singing voice, meanwhile, was merely adequate: a low, limited croon that deepened sometimes into a growl or a purr. Still, he could undoubtedly sell a song.

Worst of all, Lucien Ginsburg was Jewish, raised in a France disfigured by the racial policies of the Vichy regime; as a boy, he wore the étoile jaune, and was finally forced to flee Paris with his parents and twin sister, sheltering in the French countryside until the Liberation in 1945. He didn't even like his real name ("a loser's name, Lucien"), electing instead to be known as Serge when he performed on French television for the first time in 1958. Not, as some have suggested, because it sounded more French, but because it reminded him of his Russian émigré heritage.

For many outside France, unconvinced of his particular genius, Gainsbourg's reputation seems puzzling, while his achievements as a womaniser (his conquests included Brigitte Bardot and Jane Birkin, among literally hundreds of others) appear inexplicable; few men, sexually speaking, have punched so far above their weight. He could be charming – but also monstrous, boorish and crude. So how did he do it? It is a mystery that Joanna Sfar's mostly reverent biopic, simply titled Gainsbourg, will do little to resolve when it's released later this month.

More than Sinatra (who, let's face it, could sing a bit), more than Presley (who had, in his early years at least, an undeniable physical appeal), one could argue that Gainsbourg was the first truly modern star: a minor French club musician who seemed to decide, after years of drifting, upon his own importance, and effectively willed himself into existence – establishing himself not merely as the gifted songwriter he was, but as an actual sex symbol, a figure of 1960s hedonism and debauch to rival Mick Jagger and Jim Morrison.

Gainsbourg came from a tradition far older than rock'n'roll – though he didn't hesitate to modify his style to suit the times, announcing in 1965 that henceforth he was abandoning the classic chanson style ("too literary") to concentrate exclusively on rock. Songs such as "Je suis venu te dire que je m'en vais" and "Initials BB" proved his decision correct. But his 1971 LP Histoire de Melody Nelson, conceived and arranged with composer Jean-Claude Vannier, remains his greatest sustained achievement: 28 minutes of dark, sleek, languid funk, lushly scored for strings, with Gainsbourg's murmured vocals so close-miked you can almost smell the Gitanes and whisky on his breath. A loose concept album, tracing the seduction of the eponymous heroine, who is seduced by the narrator only to die in a plane crash, it seemed to be a Gallic take on the orchestral soul pioneered by Isaac Hayes – but darker, more squalid and urgent. Tracks such as "L'hôtel Particulier" and "Cargo Culte" rank among his finest work.

Yet, as good as Gainsbourg's songs are – and a number are very good indeed – it seems clear in retrospect that by far his greatest talent was for the perpetuation of his own fame, a creation he tended assiduously, and took care to nourish with frequent bouts of outrage, both at home and abroad.

The various scandales of his life are well known, and Sfar's film runs through them dutifully. The brief, stormy partnership with singer France Gall, for whom he wrote not only the Eurovision-winning "Poupée de Cire, Poupée de Son", but its follow-up, "Lollipop", a barely-disguised ode to oral sex, the subtext to which the 18-year-old singer claimed later to be oblivious. (Interestingly, in the new film's telling, Gall fully understands the song's meaning from the beginning); the time with Bardot, yielding the Initials BB and Bonnie and Clyde albums; 1969's fluttery, orgasmic "Je t'aime... moi non plus", supposedly recorded while Gainsbourg and then-lover Jane Birkin were engaged in intercourse (in fact, they were in separate booths in a studio off Marble Arch) – the result being banned by the BBC and denounced by the Vatican. (In a delicious aside, Gainsbourg urged the Pope to reconsider, citing the song's "almost liturgical" melody.) And, lest we forget, 1975's strangely upbeat Rock Around the Bunker LP, a concept album about the Nazis...

At some point, however, the controversy began to overshadow the work. Even a casual YouTube search will reveal the unforgettable moment, in 1986, when Serge met Whitney Houston, a fellow guest on US host Michael Drucker's Saturday night variety show. The encounter is better witnessed than described, though it is arguable that neither Houston nor Drucker were ever quite the same again. Rather less well known, but perhaps more revelatory, is another TV encounter from the same year, this time in France, when Gainsbourg (once again rowdy, dishevelled, clearly inebriated) rounded on Catherine Ringer, a singer – today best known as founder of the band Les Rita Mitsouko – and former porn actress. He called her "a filthy whore," a puzzling criticism from the old roué; Ringer responded with scorn, dismissing him as "a bitter old drunk". "I used to admire you," she added. "But now you're just a disgusting parasite."

Was Ringer correct? The evidence, by this time, seemed to support the newcomer rather than the legend. His drinking, never less than dedicated, had worsened, and his health had deteriorated. He was frequently in trouble with the law – notably, for burning a 500 franc note on television (he was protesting excessive taxation). A reggae version of the French national anthem, recorded in Jamaica in 1978, had the curious distinction of earning him the enmity of both the Front Nationale and Bob Marley, who was reportedly incensed that Gainsbourg had coaxed his wife Rita to sing sexually suggestive lyrics during his sessions there.

Then, too, there was the question of his music, which had by now declined steeply in quality. There were still flashes of the old wit, the playful love of language that had once earned him the envy and admiration of peers such as Boris Vian and Jacques Dutronc – albeit mostly, now, in the form of puns: "beau oui comme Bowie". But mostly the sound had ossified into a synth-driven bump-and-grind, desperate to appear contemporary, with lyrics that read like a letters page from Razzle.

His penultimate album, 1984's Love on the Beat, duly served up more of the old provocation, this time via a "scandalous" duet with his then 12-year-old daughter Charlotte, on the single "Lemon Incest". (Another pun, this time on "un zeste de citron".) The song was actually a transcription of a Chopin étude – but few were listening to the music. If nothing else, it deflected attention from some of the album's more truly disturbing elements – notably, a woman's screams on the title track, suggesting a rather different type of "beat" was taking place. Gainsbourg appeared on the album's cover in drag, which should have been warning enough.

Looking at Gainsbourg today, you have to wonder whether he was subconsciously projecting himself into the role of the very women he seduced and abandoned. He had already created an alternate persona – Gainsbarre: the "evil" side of himself, responsible, he claimed, for the bad, bad things he did and said – and there seemed a strange duality in him, a willingness to be both torturer and victim, lecher and romantic, coupled with an almost existential yearning for oblivion.

Thereafter came more and more incidents of public drunkenness and collapse, bouts of hospitalisation – for liver surgery that he steadfastly denied was in any way connected to cirrhosis – and a handful of increasingly bizarre, bad-tempered and incoherent TV appearances. To those unconverted to his talent, the master of French song was in danger of becoming little more than a Gallic Oliver Reed.

Yet in his homeland, he remained mostly beloved, indulged, even respected. To younger fans, the appeal is obvious: he was a bohemian, a libertine, whose very existence served as a rebuke to bourgeois society. But even among older, more conservative citizens, there was mostly affection, and sometimes fervent adoration – a situation which highlights the essentially canonical nature of France's artistic establishment.

A self-styled outsider – dogged perhaps by the memory of being forced to wear that yellow star – Gainsbourg had little in common, either artistically or temperamentally, with the grey eminences of the Académie Française or the Parisian salons; one struggles, for example, to imagine him chatting cordially with the likes of André Malraux or Jean Anouilh. But he clearly relished the status of national treasure, enjoyed the attentions of autograph-seeking fans and the clamour of photographers; and understood that at some level, and entirely on his own terms, he had attained his own, legitimate place in the French cultural firmament.

And so it proved. On his death, in 1991, France's then-president, François Mitterand, declared that he was "our Baudelaire, our Apollinaire... elevating popular song to the realm of art", while French culture minister Jack Lang noted that he personified "a certain ideal of freedom". Whether the line was spoken with admiration, envy or simply an understanding that the moment required some response, the effect was the same: Paris came to a standstill for his funeral, and his residence – at 5 bis, Rue de Verneuil, in the 7th arrondisement – fast became a site of pilgrimage, remembrance and bad graffiti.

Call it a cultural difference. Where the British media takes pleasure in cutting its public figures down to size, France maintains a notably softer, more benevolent approach, whereby the serial infidelities, bastard offspring, drug addictions and serious illnesses of its biggest names are generally considered outside the purview of the general public. Who, for the most part, appear to prefer it that way. There is no arguing, it seems, with the cult of Gainsbourg.

"I've succeeded at everything except my life," Gainsbourg once remarked, sadly. Yet the best of his more than 300 songs remain vital and incisive, and attest, far more eloquently than his scoundrel persona, to a considerable talent – and his enduring importance.

'Gainsbourg' (15) is released on 30 July