LONDON — Can beauty be stifling? Paris puts that proposition to the test, a city manicured to perfection that has confined its immigrant underclass to the invisible suburbs and burnished every surface of its seductive allure.

Certainly, a lot of young Parisians have voted with their feet, moving across the Channel to Paris-on-Thames, aka London, where they come not so much in search of jobs — although there have been more of them — as of the global swirl: that raucous mix of innovation and grunge missing in a too-perfect Paris.

A new lycée, a new radio station (French Radio London) and a new electoral constituency including Britain all testify to the exodus, as did the appearance here last week of the French Socialist candidate François Hollande, otherwise known as “Monsieur 75 percent”: more on that below.

Nobody knows exactly how many French people have moved — as European Union citizens they don’t need to register — but more than 300,000 now live in London, making it the sixth-largest French city. Most are under 40. They learn English and they learn that globalization is not merely the catalogue of woes so laboriously laid out by the French left over the past couple of decades.