With divorce negotiations between the UK and the EU set to begin in earnest in the coming weeks, at the top of the agenda is striking a deal for what to do with the kids – namely the 2.9 million EU migrants living in the UK and the 1.2 million British migrants living in the EU.
Many of those British immigrants living throughout the EU call France home and many of the 2.9 million EU immigrants in the UK are French.
So how do the two countries' expats square off against each other? How many are there, where do they live or why do they come and what good do they do are just a few questions we try to answer.
How many French people live in the UK?
A diplomatic source at the French Ministry for Foreign Affairs told The Local there were around 128,000 French nationals officially signed up to their register of UK residents.
However the real figure is likely much higher.
"Registration is not obligatory and doesn't correspond to the real number of French people in the UK," the Ministry told The Local.
"We estimate that the total number of French residents in the UK is between 250,000 and 300,000."
How many Brits live in France?
Again the exact number is hard to come by.
A 2012 study by Britain's Institute of Public Policy Research put the number of Britons living in France in 2012 at 253,000.
But in 2013 the French statistics agency INSEE only had some 153,000 Brits officially registered in France.
The most recent survey, carried out in January 2017 by Britain's Office of National Statistics, put the number of Brits living in France at 157,000.
But the number could be greater, especially if we take into the account those who may not officially live in France but spend a large chunk of the year here.
Where do the French live in the UK?
The cliché goes that London, or "Paris on Thames", is full of French people, indeed one street in South Kensington that's nicknamed “Frog Alley” is lined with French bookshops and bakeries catering to the resident French population.
According to the UK Office for National Statistics (ONS) 2011 census, 51 percent of French people living in the UK live in London.
But the French Consulate reckons some two thirds of the 300,000 French people it believes are living in the UK, live in the capital, so around 200,000.
So where do the rest of Britain's French population live?
The French consulate says the rest of the French population is concentrated in other urban areas of the country, mainly Birmingham, Leeds and Manchester.
The least popular destinations for France-born residents were the North East of England, Wales and Yorkshire.
Scotland wasn't featured in the census, but the French Consulate reports 5,532 registered French nationals in Edinburgh – a higher figure than the whole of the North East and Wales put together on the ONS census.
Where do Brits live in France?
In contrast to the French in the UK, the majority of Brits in France are certainly not concentrated around the capital Paris.
According to INSEE's stats some 8,529 Brits live in Paris, only 5.5 percent of the overall total. Unlike the French in the UK, Brits in France like what the countryside has to offer.
After Paris the department with the most Brits is of course Dordogneshire, where 7,316 Rosbifs live among the rolling hills and rivers.
But plenty of other departments in France contain a large number of Brits too: There are just over 6,000 in Charente, western France, some 4,500 in the department of Haute-Vienne, next door to Dordogne, over 4,000 in Côte d'Armor in northern Brittany and a similar number in Yvelines in the greater Paris region.
The only place they tend to avoid is the east of the country. Check the map out below.
Who are the French expats in the UK?
The UK appears to be a bigger draw for French women than men. The French consulate's 2013 registry was made up of 55 percent women, 45 percent men.
Those who come to live in Britain are primarily young, with 40 percent of them aged between 18 and 40.
That goes along with the idea that the French who move to London are largely young professionals. If you ever take the Eurostar train back to Paris on a Friday night, it appears full of young French people heading home for the weekend to get their suits washed and a decent meal.
One interesting stat is that the average length of time a French expat spends living in the UK is 5.7 years, backing up the idea that French expats will tend to return home to the mother country at some point.
Who are the Brits living in France?
The idea that Brits in France are all retired folk spending their pensions and their time drinking rosé wine in the gardens of their refurbished cottages is somewhat a myth.
In reality most Brits living in France are working for a living. The data backs this up.
Statistics from INSEE reveal that there are some 70,000 Brits in France aged over 55, and many of them will still be working full time of course.
There are around 55,000 Brits in France aged between 25 and 54 and 11,000 aged between 15 and 24.
Many are couples in their 30s and 40s with children.
According to another study by Britain's Institute of Public Policy Research the percentage of British nationals living in France who were pensioners was only 22.5 percent.
So to cut a long myth short, most expats are here working in some form of another.
While there is no stat we found for how long Brits will live in France, anecdotally many appear to be here for good, which is why they tend to buy property, unless circumstances, like Brexit, force them to return home.
What do the French do in the UK?
A common image is that French people in the UK all work in the London finance scene. And in fairness, many do.
French newspaper Le Figaro reports that an estimated 60,000 French people work just in the financial centres of The City of London and Canary Wharf.
Kumaran Surenthirathas, head of front office at Eximus recruitment firm says “in some business centres they [French people] outnumber British people”.
Many French living in the UK are there to study. In 2013 there were 11,725 French students in UK higher education, although some figures put the number as high as 25,000.
What do Brits do in France?
Well there's the retired folk who do what they want, but after that Brits living in France do any number of jobs from working behind bars, teaching English, selling houses, translating, working in finance, looking after French children, writing French news. The list is endless.
There are also some 4,000 British students studying at French universities.
Why do the French move to the UK?
The popular idea is that French people ‘flee' extortionate taxes in France for the UK's lower rates and higher salaries. But this doesn't tell the whole story of why French natives are taking the way trip across the Eurostar.
"They are drawn by geographical proximity, the language, a dynamic labour market and low unemployment -- 5.6 percent compared to 10.4 percent in France in July 2016, writes AFP in a report on the French in London.
The move can be to seek out new job opportunities and further careers in sectors that are more prominent in the UK. Britain has a stronger economy and more flexible approach on employment compared with France.
And why do Brits move to France?
While we have no official survey to rely on, the reasons given for moving to France are, in no particular order: jobs - whether to find a new one or move with a company, lifestyle - many simply want to get away from the "rat race" and enjoy the slower pace of life, the sun - let's face it many move for the warmer climes, property - basically selling up in the UK and buying in France means you can in general get far more for your money and love - yes believe it or not we'd follow our French lovers anywhere, even France.
An expats survey found that those who had moved to France noted a jump in the quality of life, particularly when it came to work life balance.
Which group brings the most to their adopted country?
Both contribute enormously of course.
French financiers are helping the City of London hold on to its status as Europe's banking capital as well as paying plenty of taxes into state coffers, not to mention contributing to the UK's wonderful cultural melting pot, especially in London.
The French consulate in London says there are more than 3,000 French businesses employing nearly 400,000 people in the UK. with French companies in Britain turning over €120bn annually.
For their part Brits are helping keep alive villages across rural France, a fact even once recognized by ex-President Jacques Chirac.
By buying property in towns and villages across the country they have helped prop up the property market, keep stores and cafes and even local schools alive. Most integrate into local life, many even becoming local councillors.
On the business side of things, the Franco-British Chamber of Commerce in Paris boasts some 700 members.
So as far as bargaining chips go, both the French in the UK and the Brits in France are pretty valuable.