The Bugatti Queen ny Miranda Seymour

From postman's daughter to racing's golden girl

Like our very own Elizabeth II, elegantly poised at the centre of a bunch of dark-suited male Commonwealth heads of state, Hélène Delangle poses. It is early June 1935. In white dress and wide-brimmed hat, clutch-bag casually clasped beneath steely biceps, she is slender, laughing and confident of her imperial, imperious position. Twelve male racing-drivers loll around their queen, louche and comfortable. Only one of these apostles stands square to the camera. He is Louis Chiron, the one in the darkest suit, the one with the steadiest, scariest smile.

The caption to this photograph suggests that readers should note his "hostile arm language" but we have already learnt to mistrust this man. It was he who blithely accelerated past the crash that killed the gallant Henri de Courcelles. And, at a party in Monaco 14 years after that photograph was taken, it was Chiron who denounced Hélène as a Gestapo agent. It was almost certainly a lie but, whether he was her Judas or her Nemesis, with this accusation Chiron effectively finished her.

Hélène was a phenomenally successful racing-driver, at a time when huge crowds flocked to the tracks to see this new, often lethal sport. As Hellé Nice (a pleasingly evocative pseudonym), she took on the men, eschewing any handicap offered on the grounds of her being a feeble woman. Too often for their equilibrium, she won, gathering trophies and enemies on the way. She seems never to have known the meaning of fear, and she had the showgirl's almost instinctive knowledge of how to work a crowd.

Towards the end of 1930, for example, she was in America, driving big fast cars over infamous dirt-tracks, the only European woman to have crossed the Atlantic for such a purpose. In the steep bowl of a track in North Carolina she hit a pothole at great speed and crashed into the barrier. The car overturned and came to rest balancing on the high parapet at the vertiginous edge. Hélène emerged from under the vehicle and ran back to the grandstand, waving her trademark white beret. "And then," she told an interviewer, "I thought I might as well give them a song. So I did."

Her life wasn't easy. Though she preferred the year 1905, she was actually born in 1900, the daughter of a French provincial postman who died when she was four. Her disapproving family was frequently submerged in gloom and disaster but she escaped as soon as possible for Paris, where she did a spot of modelling before training as a dancer. The zenith of this first career was probably a nearly-nude performance of Daphnis and Chloë at the Ritz - but such activities began to feel a little tame. Always motivated by preternatural physical courage, she decided to test herself further. During the 1920s she swung high on a trapeze above a gasping circus audience, she climbed any Alp within sight and she skied like a demon. She was blessed or cursed with a ferocious competitive urge.

At 29, while avoiding an avalanche, she damaged her knee and gave up the dancing business in favour of motor-racing. Already fighting fit, she trained intensively, strengthening her body for the strain of heaving heavy cars around steeply-banked race-tracks, against all-comers of either gender. And she was astonishingly successful. For six years, she was racing's golden girl.

Miranda Seymour came across her by chance. Hélène was little more than a half-forgotten legend when the chance discovery of her old (and, happily, annotated) scrapbooks, at a French flea-market, gave Seymour the material help she needed. Immediately attracted to her subject, she determined to try to do her justice. It was a challenge. Seymour is a novelist as well as a celebrated biographer, reliable and scholarly. This time, the hard evidence available for her scrutiny was scanty and she chose to allow the brim of her novelist's hat to slip over an eyebrow as she wrote this book.

The result is an interesting hybrid of rigorous fact and fanciful reconstruction. But, rather like a converted oast-house, it works. At the start, the wind seems to be stirring the Seymour imagination into flights of creativeness that verge on the risible. By the end, the bald and tragic truth has become not only inevitable but plausible in nearly every detail (except, perhaps, in her hypothesis that Hélène suffered sexual abuse as a child, which seems to be going a little too far). When she is following a hunch rather than analysing documents, she indicates as much in the text. Sometimes, when her subject disappears, she resorts to more general history. Her chapter on the subterfuges necessary for survival in occupied France is an excellent and disturbing example.

With her bottle-blonde curls and her joyous smile, Hélène was racy in every sense. Wisely, Seymour makes little effort to tot up her innumerable lovers, though she observes that a title had a way of attracting Hélène's attention. The Spanish count and the Savoyard and Romanian princes follow each other into her arms with grand insouciance, though the formidable French Baron (de Rothschild) merited a little more discretion, whenever he found time for her - between translating Elizabethan poetry, inventing the first windscreen-wiper and bagging the odd tiger.

Hélène's annus horribilis was 1936. After a horrifying crash in São Paolo, she was laid out among the dead by the track. Astonishingly, she recovered well enough to take more world records the next year, but her glory days were numbered. Her old age was pitiful. Penniless, disowned by her sister and deserted by the last of her lovers, she was cared for by a charity until her death. For a while, she worked as a chauffeur but it wasn't a success. Years earlier, a journalist eager to experience the thrills of the track had persuaded Hélène to take her out: the journalist lasted half a lap before fainting. It is satisfying to learn that, in her last job, her driving was described as "not of a kind to reassure passengers".