Tens of thousands more UK citizens applied for citizenship in other EU countries in the 12 months after the Brexit vote than in the previous year, according to data obtained by the BBC.
Ireland received by far the most applications for dual nationality.
But for all the countries that had data covering July 2016 to June 2017, applications have more than doubled.
In other countries, which only had data for calendar years, there was a sharp rise from 2015 to 2016 as well.
Among well-known UK citizens to apply for citizenship elsewhere in Europe is the Oscar-winning actor Colin Firth - it was confirmed last week that his application for Italian citizenship has been successful.
Yes, even Mr Darcy is feeling flustered.
Reality Check and Radio 4’s More or Less contacted all EU countries to ask about the number of citizenship applications they had received from British people, before and after the referendum in June 2016.
It has not been possible to get full figures for every country, but the data we have compiled shows just how many people are taking precautionary steps in case the Brexit negotiations fail.
In the 12 months before the referendum, 25,207 Britons applied for Irish passports; in the 12 months directly after the vote that number rose to 64,400.
Sharp increases have also been seen elsewhere. In Spain the numbers rose from 2,300 before the referendum to 4,558 after.
In other countries around the EU - Sweden (from 969 to 2,002), Denmark (from 289 to 604) and Poland (from 152 to 332) for example - the number of applications also more than doubled.
Then there are countries where data is made available in slightly different ways.
In Germany it comes state by state - so in Berlin there were 60 applications from British citizens in the year before the referendum, and 810 in the year after.
France meanwhile provides figures on a calendar year basis, and again the increase is clear - there were 385 applications in 2015, rising to 1,363 in 2016, and rising further to 2,129 in the first eight months of this year.
Of course this is not simply a one-way street. There are more than three million EU citizens living in the UK who are equally worried about their future status post-Brexit.
And again, the number of citizenship applications in the UK is striking. 15,871 people from EU countries applied in the 12 months before the UK voted to leave the EU; in the 12 months after it was 28,502.
Perhaps these figures don’t come as a surprise.
But they are a reminder of why the issue of citizens’ rights is at the centre of the current Brexit negotiations - and why all sides say it is a priority to resolve.
Brexit often seems to be about complex and distant concepts. But these are real people, worried about the future for themselves and their families.
Additional reporting by Phoebe Keane for Radio 4’s More or Less, Tamara Kovacevic, Bethan Morrish, Joey D’Urso and Robert Cuffe.
You can hear more about these statistics on More or Less on BBC Radio 4 at 4.30pm on Friday 29 September or on BBC iPlayer Radio.