Basildon-en-Provence, the grey French town that is sorely tempted by infamy

How could a culture which produced Paris and Avignon and a thousand charming, small towns also produce Vitrolles?

Vitrolles is Basildon-en-Provence; or New Jersey-sur-Mer. It is a town of pink and orange concrete abstractions, built in the Seventies and Eighties but already crumbling, a joyless, and jobless, little town of nearly 40,000 people.

It occupies a narrow strip of land between Marseilles airport, three motorways, two oil refineries and a drab, polluted lagoon at the mouth of the Rhone. At its back stand the cliffs of the Luberon hills, a reminder of another Provence of lavender and wily peasants and holiday homes.

Vitrolles was put here, 25 years ago, to relieve the demographic pressure in Marseilles and was then, for the most part, forgotten. It has among the highest unemployment and crime rates in France. White, Arab and black youth gangs, transplanted wholesale from the old port, pursue their old battles here.

Vitrolles also has a trendy Socialist mayor, who sums up much of what went wrong with the socialist revolution in the Eighties: the blow-dried, greying hair; the casually worn white designer scarf; the naming of unswept streets after leftist saints (Avenue Nelson Mandela; Place Olof Palme); and the multiple charges of embezzlement of municipal funds.

Jean-Jacques Anglade may not be mayor for much longer. Next Sunday, Vitrolles is expected to scream its anger at the smart metropolitan establishment which it believes has betrayed it. In the second round of a re-run mayoral election (the first was cancelled for manifold irregularities), Vitrolles is on the verge of giving the extreme right and xenophobic Front National (FN) the most important electoral victory in its history.

"It is not because the Vitrollais are fascists," said Marius Comti, 41, who works in a local coal mine. "It is because they are angry and they have no work and feel themselves abandoned. They have no love for the Front candidate. How can you like someone who shakes hands without taking off her white gloves?"

In the first round last Sunday, the Vitrollais turned out in record numbers and gave 47 per cent of the vote to Catherine Megret, wife of the deputy leader of the FN, Bruno Megret. Mr Megret was banned from running because he exceeded the spending limit before the last poll in 1985. A victory for his wife on Sunday would be a triumph for Mr Megret, 47, and confirm him as the intelligent, energetic and plausible dauphin to the throne of Jean-Marie Le Pen: a prospect many commentators in France find more distasteful and threatening than the rumbustious, one-eyed Mr Le Pen himself.

Because the centre-right candidate has withdrawn under intense national pressure, Sunday's election will be a straight fight between Madame Megret and the mayor. If, as expected, the FN wins, it will be the first time the party has won a clear majority in any election.

"This is the importance of Vitrolles," Mr Megret said in an interview at his wife's headquarters - a small flat jammed with rumpled, serious-looking middle-aged men.

"We will have taken on, for the first time, the combined forces of all the other political parties in France, and beaten them. It is a sign that the dike is beginning to crack."

The FN already controls (with pluralities not majorities) three town halls in a small arc from Orange, in the lower Rhone valley, to Toulon on the Mediterranean coast. A victory in Vitrolles would solidify this regional base. With the respectability conferred by running four town halls, the FN could hope to start winning parliamentary seats in the Midi in the general election next spring. The issues in Vitrolles may be local but, for the mainstream parties, they mirror uncomfortably the angers and anxieties of the national electorate: jobs; fears of Europeanism and globalism and loss of French identity; and the continuing revelations of graft in the major parties, especially President Jacques Chirac's neo-Gaullist RPR.

But, most of all, an FN victory would be the apotheosis of Bruno Megret, a classic French technocratic insider - former Ecole Polytechnique, former RPR - who has brought his undoubted political skills to the FN, the party of the malcontented outsider. Dissidents within the FN allege that, despite his polished and reasonable manner, Mr Megret is even more "pur et dur" than Le Pen, more ideological, more tempted to explore philosophical and actual links between the FN and neo-Nazism. A small, balding man with an ingratiating smile, he makes, at first sight, an unlikely demagogue. But mainstream French politicians fear that he might be the man to extend the FN's appeal beyond the blue-collar city outskirts and the sink towns like Vitrolles, into the bourgeois suburbs.

The big parties are pulling out all the stops to prevent a "his and hers" victory for the Megrets. The Prime Minister Alain Juppe's centre-right coalition twisted local arms to force the second-round withdrawal of their own candidate, in order to give the widely loathed socialist, Mr Anglade, a clear run against the FN on Sunday.

All of which suits the Megrets just fine. It gives them the opportunity to portray the Front National as the only party fighting against a corrupt and collusive national, political establishment. Mrs Megret bounces into her headquarters, in elegant red jacket and black skirt, but not her white gloves. She is a would-be Gallic Evita: part Parisian housewife, part excited school-girl, but also a much more impressive political operator than her opponents have admitted.

"It is they, not us, who are the anti-democrats. It is they who refuse to admit the legitimacy of the views of 17 per cent of the French people. If you don't share the national idee fixe in this country, you are branded racist, inhuman, even animals

Will she win? The miner who criticised her gloves, Mr Comti, says he believes that a "Republican reflex" - an attachment to humanist values which goes back to the Revolution - will bring out enough people to defeat the FN on Sunday.

But Mrs Megret only needs another 3.5 per cent - perhaps an extra 100 votes. And Vitrolles, the forgotten town, will be sorely tempted to have its day of infamy.