Fewer EU citizens are registering for national insurance numbers in Peterborough than before the Brexit vote, the latest figures reveal.
The statistics, from the Department for Work and Pensions, show how many foreign nationals have successfully applied for NI numbers, which are required to work or claim benefits.
Last year 4,036 people from the EU registered for NI numbers.
In the 12 months up to June 2016, the month of the referendum, 4,563 people registered, 527 more than in 2017.
The data divides the European workers into three groups.
It identifies people from the EU15, which are countries that joined the bloc before 2004, like France, Spain and Germany.
The EU8 countries joined in the 2004 enlargement, and include nations such as Poland and the Czech Republic.
The EU2, Romania and Bulgaria, joined in 2007, but could not move to the UK to work until 2014.
The biggest drop in new workers registering post Brexit was by those from the EU8 countries.
In 2017, 1,937 EU8 citizens signed up for NI numbers, 696 fewer than before the Brexit vote.
Of residents from the EU15, 220 fewer registered. And the number of Romanians and Bulgarians registering for NI numbers, actually rose by 382 or 33%.
The data does not explain why the numbers have reduced.
It could be due to post-Brexit uncertainty or other factors such as the improvement of the economies in residents' home countries. Poland, for example, currently has a record low unemployment rate.
The number of applicants from outside the EU has also decreased.
A total of 581 people from the rest of the world registered for NI numbers last year, a drop of 48 on the period before Brexit.
From outside of Europe, the area with the highest number of applications was South Asia, which includes India and Pakistan, with 237 registrations.
This, combined with a drop in the number of EU citizens applying, has contributed to a reduction in the overall number of foreign nationals applying for NI numbers in Peterborough.
During 2017 total of 4,598 people gained an NI number, a decrease of 589 on the 12 months before the Brexit vote.
The data also shows that period with the highest number of new registrations over the past four years was the 12 months up to December 2016.
The DWP says the figures should not be used to indicate immigration levels, as foreign nationals could have been in the country for some time before applying for an NI number.
Before the EU referendum in 2016 the Office for National Statistics had to issue a clarification around the data.
Nigel Farage and Boris Johnson claimed there had been a conspiracy to keep voters in the dark over EU immigration levels after there was a disparity between NI numbers being registered and official migration figures.
However the statistics body reiterated that NI figures could not be used to measure the number of immigrants, as they are skewed by short term migration and seasonal workers.
The ONS' latest nationwide immigration statistics, released last week, show net migration of EU residents has fallen to its lowest level in five years.
However net migration from outside Europe rose.