Similar demonstrations in the provinces, however, attracted only small crowds: 2,000 in Toulouse, 1,000 in Strasbourg, 300 in Marseilles. The revolt against the new law - and by proxy, the far right - has been led by prominent intellectuals and artists and seems to be disproportionately a Parisian affair.
According to the polls, more than 60 per cent of French people support the new immigration Bill, which is due to be finalised in the National Assembly tomorrow. Paradoxically, the same polls suggest that just over 50 per cent of French people support the scores of petitions of protest against the Bill, which led to Saturday's march.
The arithmetic is not necessarily as strange as it sounds: it has been clear from the beginning that the real target of the protests is Jean- Marie Le Pen's xenophobic Front National, following its electoral victory in Vitrolles, near Marseilles. This was evident from the banners and placards on Saturday, divided more or less equally between attacks on Jean-Louis Debre, the interior minister who drafted the proposed law, and attacks on the FN.
The march began at the Gare de L'Est, as a deliberate reference to Jews deported from that station during the Second World War. In an atmosphere of solemn carnival the parade filled the whole of the Boulevard de Magenta - at least one mile long - by the time the last marchers left the station square.
The protesters were mostly under 50; mostly, but not all, smartly dressed; mostly, but not all, white; mostly, but not all, leftish in their politics. Although some of the most famous petitioners (Catherine Deneuve; Isabelle Huppert) were nowhere to be seen, the marchers did include the cinema director Bertrand Tavernier, the wife of the late president, Danielle Mitterrand, the former Socialist prime minister, Laurent Fabius, and the Communist Party leader, Robert Hue.
"Nous sommes tous, tous des immigres [We are all immigrants]," the marchers chanted. According to a recent demographical survey, this is not a huge exaggeration. Something like 20 per cent of the French population is descended from immigrants who arrived in the last 70 years. "What of Joyce, Wilde, Hemingway?" asked one placard, referring to famous - but certainly not illegal - literary immigrants to France.
The apparent confusion between legal and illegal immigration runs throughout the protest against the Debre law. The protest leaders argue that the centre-right government of Alain Juppe - and the whole of French politics - have become infected by Le Pennist ideas. They have seized on the law, months after it was first promulgated, as a way of fighting back against the Front.
But the law, though clumsily drafted, is mostly a tightening of procedures against illegal immigration which have existed for years. Its most controversial clause - requiring French people sheltering certain categories of foreigners to inform the authorities when the foreigners move on - has already been dropped. Though impressive and well-intentioned, the protests risk alienating a section of the working and lower-middle class, already vulnerable to the FN assertion that the nation's elite cares more for foreigners than for the French.
Police yesterday cleared 400 "sans papiers" or illegal immigrants from the Saint Jean-Baptiste church in Belleville in the 19th arrondissement of Paris. The immigrants, mostly ethnic Chinese, occupied the church on Saturday to protest against the Debre law.Reuse content