AMONG the most contentious issues in negotiations over Brexit is the status of expatriates. Over 3m people from European Union (EU) countries outside the British Isles currently live in Britain, and around 1.2m Britons reside elsewhere in the EU. In theory, a “hard Brexit”, in which the EU’s free-movement guarantee is abruptly revoked, could force both groups to uproot their lives and move if they cannot secure new visas.

Such an exodus would not only cause widespread disruption in the short term, but also inflict a heavy toll on Britain’s demographic profile. Foreigners of prime working age who live in Britain are far more likely to have jobs than their peers elsewhere in Europe are. Fully 78% of immigrants to Britain aged 25-49 are employed, compared with 68% in Germany (whose ratio is the second-best in the EU) and just 58% in France. And in addition to luring other countries’ workers, Britain also excels at exporting its own pensioners. Nearly a quarter of a million Britons aged 65 and over live in other EU countries—120,000 in Spain alone—whereas only 85,000 of those aged 65 and over from elsewhere in the EU have settled in Britain.

A deal allowing both groups to stay put could well be reached. Nonetheless, the threat of Brexit-related upheaval already seems to be influencing decisions. Since the British public voted to leave the EU last June, the country’s net annual migration rate from the rest of Europe has slumped from 189,000 to 127,000. The biggest decline has come from the 12 countries, mostly in eastern Europe, that joined the EU in 2004-07 and have sent a total of 1.5m migrants to Britain since. Not only were inflows from that group—which includes Poland, Hungary, the Czech Republic, Romania and Bulgaria—20% lower in the year to March than they were during the previous 12 months, but the number of nationals from those countries departing Britain rose by 70% as well.

Moreover, even if all current expatriates are allowed to stay, Brexit may still take a bite out of their purchasing power. In the wake of the Brexit vote, the pound has slumped against the euro. As a result, the maximum British government pension is now worth barely more in euros than it was in 2012. Such financial woes could still lead many sun-seeking British pensioners to abandon the Costa Brava and settle for merry Margate.