This surprised me when I first heard it some months ago, so I thought I would do a little research of my own to validate the claims. Nantes is the regional capital of the Pays de la Loire region of France, has a population of just over 280,000 (many of whom will not be French, as it is a big University City and also popular with the British) and ranks as the 6th largest French city by population.
According to a BBC World Service report from a few years ago the number of French people living in London stood at over 300,000. I think that is quite staggering and would make London the “6th biggest French city” in terms of the number of French living there.
I wonder which country gets the better deal here – or whether it matters. Most of the French living in London are likely to be young, salary-earning, tax-paying professionals, and so not a big drain on UK social care resources. I would imagine that a good many of the Brits living in and around Nantes will be a little older and so perhaps posing more of a strain on the French health system, but they would generally draw a UK pension and then spend the money in France. they might also operate a gite or other accommodation and so bring money into the area that way.