Unlike the British, the overseas vote is of importance to the French political parties as they target their over 100,000 expat citizens registered to vote and living in London.

http://www.guardian.co.uk/world/2012/feb/18/french-expats-london-election?newsfeed=true

Welcome to “Londres”. In a closely fought race, the French residents of the capital are being courted as never before. Legislation passed by the French parliament in 2008 gave citizens who live abroad the right to elect their own politicians, in constituencies created specifically for expatriates. For the first time this year, national assembly elections – to be held in June – will effectively return an MP for Britain. No wonder, then, that interest in London in the presidential race, held a month earlier, has spiked.

“London carries a lot of weight, electorally speaking,” says Axelle Lemaire, the Socialist party candidate for northern Europe, a constituency that incorporates 10 countries including the UK and the Baltic states. “Within those 10 , 80% of the electorate live in the UK. Of them, 80% are based in London.”

There are 102,470 French voters registered in the UK, and Hollande is set to visit London later this month. The number of French people living in Britain has risen every year since 1991, jumping by almost 10,000 in 2006, the biggest single gain in two decades. London’s high-profile French residents include Arsenal manager Arsène Wenger, author Marc Levy and pop singer Renaud.