There are many French people living in London, but does it really have the sixth highest number of any city, asks BBC News. French media have been debating the accuracy of this often-repeated claim.
In a speech last year, Boris Johnson, Mayor of London, recalled a meeting with France's former prime minister, Alain Juppé, who was mayor of Bordeaux at the time.
Juppé told him, Johnson said, that he had the honour of representing 239,517 people in Bordeaux, the ninth biggest city in France.
"I got the ball back very firmly over the net, folks," said Johnson, "because I said there were 250,000 French men and women in London and therefore I was the mayor of the sixth biggest French city on earth."
Johnson wasn't the first to make this statement about the size of London's French contingent. It was aired in the French media when Nicolas Sarkozy visited London as French president in 2008 and has been repeated many times since, including by the BBC.
There is a political dimension to it, because it illustrates the idea that the UK's capital is booming, good for entrepreneurs and brimming with jobs.
Johnson says there are 250,000 French people in London. Other British estimates say 300,000-400,000. The figure that is quoted most often is 300,000 which is attributed to the French consulate in London.
When asked, the consulate said this figure was for the whole of the UK, although most of those French people would be in the capital.
This is at odds with the figure from the UK's Office for National Statistics (ONS). It carries out a household survey once a year and its most recent one says there are 123,000 French nationals in the whole of the UK and only 66,000 are in London.
But these ONS household surveys don't count everyone. For example students in halls of residence and people in care homes are left out.
The UK Census does count this, and the 2011 Census says there are 86,000 people in London who hold French passports.
So why are the numbers so different? The ONS is absolutely sure about its figure. But the French consulate says the real figure is much higher.
Xavier Chatel, press spokesman at the French consulate, concedes there is probably no "official" measure.
"This is Europe so people are free to come, free to go, there's no authoritarian obligation to register somewhere and therefore there is a certain degree of uncertainty about them."
But he says that using data from the UK's electoral commission, the Department of Work and Pensions, Census data and the consulate's own register of people they can come up with a reasonable estimate of 270,000 French people living in London.
he consulate defines London as the city plus "the south eastern quadrant of the UK including Kent, Oxfordshire and maybe Sussex too".
This is quite a generous description of the London area - it includes Oxford, a city in its own right about 60 miles away from London. Kent and Sussex meanwhile, stretch right down to the English Channel.
But assuming the ONS number and the French consulate number are the best estimates, how do they measure up against the population of French cities?
Read more of this report from BBC News.