Sagan received an appropriately admiring obituary in the Telegraph.

Françoise Sagan, who died yesterday aged 69, exploded on to the French literary scene in 1954 with her first novel, Bonjour Tristesse, written when she was just 18.

The novel tells the story of a rebellious 17-year-old whose manipulations destroy the relationships between her libertine father and his various women. Published just as teenagers were emerging as a distinct social group, it was an immediate succes de scandale, delighting and shocking with its worldly cynicism and suave amorality. It won the Prix de Critiques and earned Françoise Sagan £500,000 and a papal denunciation. François Mauriac, France’s most respected novelist, hailed the talent of “ce charmant petit monstre” on the front page of Le Figaro.

Yet though she continued to produce novels and plays at a rate of roughly one a year, Françoise Sagan’s writing lost its astringency and she began to be dismissed as a lightweight author of women’s romantic fiction – more Mills and Boon than enfant terrible.

Instead, propelled by her celebrity and wealth, she became better known for her rackety lifestyle – sports cars and crashes, serial lovers, addictions to gambling, whisky and drugs and run-ins with the tax authorities. An opinion survey conducted a few years after Bonjour Tristesse showed that most people in France thought her a film star, rather than a writer.

Fame – or rather, the Paris Match version of celebrity – clung tenaciously to Françoise Sagan. Moody, gamine and matchstick thin, elfin face peeping out from under a mop of cropped hair, in the 1950s and 1960s she seemed the epitome of Parisian radical chic. A frequenter of cafes, nightclubs and student barricades, she dined with Sartre, Hemingway, Henry Miller and the young François Mitterand. Vanessa Redgrave admitted that she began smoking after reading that Françoise Sagan always smoked Gauloises and had a cup of coffee for breakfast: “Immediately, I decided this was sophistication itself.”

Her literary oeuvre offered a version of France in which personal responsibility counts as nothing against stylish living – a principle she was determined to live by. One of her tricks was to arrive at a nightclub with one escort and leave with another; and she always parked her sports cars outside the door of her destination whatever the traffic regulations. As if to illustrate the point, a cover of one of her novels showed her aged 19 or 20, draped in a long leopardskin coat over the door of an open-topped Jaguar, dark circles under her eyes. Yet despite the hype that inevitably accompanied everything that she did, she managed to remain remarkably honest about her own limitations as a writer and as a person.

When offered membership of the Academie Franaise, she turned it down: she had read enough good books, she said, to recognise the difference between the literary merit of Bonjour Tristesse (which she claimed never to have re-read) and the fuss made about it. She never uttered a word of regret for her “unbridled life” but confessed that she had never really grown up: “as a result I don’t really understand adult values and I never will”. …

Françoise Sagan’s life was more colourful copy than her books. Flushed with the success of Bonjour Tristesse, she sped down in her new Ferrari to St Tropez where she turned her publishers’ cheque into gambling chips, whisky and lines of cocaine – and indulged a prodigious appetite for sex. “She tried every experience,” a former lover recalled, “with two persons, with a woman, with three, four. She was in the avant garde, La bande Sagan – a group, with Juliette Greco. They were drunk almost every night and they were a most crazy group. La bande Sagan was the top of sophistication.”

In 1957, she survived a serious accident when her Aston Martin overturned on a sharp bend and left her in a coma for three days. Soon afterwards she married Guy Schoeller, a publisher 20 years her senior. When that broke down, she married an American sculptor, Robert Westhoff. They had a son, but that relationship too ended after only a year. Marriage, she reflected, is “like the matter of asparagus eaten with vinaigrette or hollandaise – a matter of taste but of no importance”. …

Françoise Sagan maintained her reputation as the voice of hedonistim with a fund of bons mots: “You should celebrate the end of a love affair as they celebrate death in New Orleans, with songs, laughter, dancing and a lot of wine”; “a dress makes no sense unless it inspires men to want to take it off you”; “Every little girl knows about love. It is only her capacity to suffer because of it that increases.”

But by the 1970s, with her brown hair turned miraculously blonde, fast living was taking its toll. Her passion for gambling became so intense that she asked the Ministry of the Interior to ban her from casinos. She had several brushes with death and in 1978 gave up drinking after a misdiagnosis of cancer of the pancreas. Her drug abuse landed her in court on several occasions and led to a demand from the Right-wing politician Jean Marie Le Pen that she be guillotined.

In 1990 a satirical puppet show on French television presented her as a disshevelled old bat butting in on every conversation, wild-eyed and gesticulating. “I believe I have the right to destroy myself as long as it doesn’t harm anyone,” she said. …

[S[he never quite managed to exorcise her demons. In 2001 she was convicted of tax fraud and given a one-year suspended jail sentence for failing to declare $726,000. But she said: “I always believe things are going to work out. Every time I see a film about Joan of Arc I’m convinced she’ll get away with it. It’s the only way to get through life.”