Meeting Berthonneau is like coming face to face with a Mediterranean version of the Wizard of Oz. Three hours before the annual Joan of Arc festival in Rouen in May, the wiry, leather-jacketed, boffin-haired 33- year-old is to be found tucked away under a bridge, making minute adjustments on what looks like a recording studio mixing desk. Hundreds of white flexes trail across the concrete to skips packed with sand and explosives.
Firework man has clearly evolved - rather than groping for touchpaper in the dark like his forefathers, Berthonneau devotes so much attention to his computer screens that he can only watch his grands spectacles afterwards, on video. He has been a pyromaniac ever since working in a steel foundry at the age of 17 ("If I see one flame, I am happy"). Although the working method he has developed over the years might seem coldly clinical (a repertoire of 450 effects, each designed down to the last grain of barium at his Camargue home), he argues in energetic Franglais that his vision is as personal as that of any artist. "What I do is art, pure art. It's an act of self-expression that takes months of work to realise. I am not at all interested in simply demonstrating the latest effects."
Over the course of the evening, he lobs various rhetorical devices ("I try to play the fire, not play with fire", "They call it feu d'artifice, I call it feu d'authentique") before reaching a stream of consciousness crescendo: "When you watch, you have no feet, no legs and no body and you're just like ooh, ooh, look... in a magical world." If his critical vocabulary sounds improvised, that's probably because in France, as in England, fireworks are still little more than means to civic celebration. But his theories cannot be easily gainsayed: since fire is such a primitive energy, why shouldn't a firework display be as gripping, as overpowering, as a piece of theatre? The work in London, a homage to this "material", will, he insists, be theatrical, both in its use of light and space and its deployment of over 30 young local actors, together with assorted musicians and sculptors.
As the son of an actress, who spent his childhood days in Paris watching her at the experimental theatre Le Mouffetard, and who went on to join, after leaving school at 14, interventionists Ilotopie, and Catalan theatre group Els Comediants, Berthonneau's incorporation of live performance is clearly no stunt. His past record shows a desire to make the crowd think: despite the protestations of the mayor of Martigues, he uses an image and music-assisted display celebrating the town's liberation from Nazi occupation to draw connections between Hitler and Le Pen. Nevertheless, his suggestion that the Rouen event will help introduce opera and classical music to a wider public smacks more of grandiosity than artistic purpose.
And indeed, apart from the opening procession of 2,000 torchbrand-wielding schoolchildren, snaking through the streets from the cathedral down to the Seine following two flaming iron-birds (smaller versions of the Heath Robinson contraptions that stunned Londoners two years ago), the 800 kilos of powder are, frankly, a damp squib. Berthonneau's monochrome sets (all gold fountains one minute, symetrically exploding blue rockets the next) are the height of good taste, but the accompanying soundtrack, pumped out of 70 amplifiers, sinks them. Every Maria Callas warble, every surge of Mozart's Requiem is answered by a corresponding thrust of the flame- throwers lining the bridge or an accumulating mass of stars. The result resembles a hi-fi graphic equaliser - technologically impressive but artistically inert.
Berthonneau is apologetic afterwards. "There wasn't really enough money to respect the scale," he mutters. "I wanted to do a piece specifically about Joan, exploring her virginity, her courage, her life, but it wasn't possible," he shrugs. "When the show is going OK, the public feels something. When it's going really well, it can be a miracle, but a miracle can't happen every time." There may be a miracle in London this weekend, but Berthonneau is not guaranteeing one. After 2,000 years, the art of fireworks is still a touch and go affair.
Sat, 10pm, Battersea Park, London SW11; tickets (pounds 1) from the site box- office 12pm-8pm from ThursReuse content