Along with banks that have signalled they will be moving jobs abroad, Brexit will probably see the European Banking Authority leave London -- and rival cities are jockeying to be its next host.
The London headquarters of the European Union's financial regulator, in the Canary Wharf district, has 170 staff members from 27 of the 28 European Union nations.
Brexit is "a major talking point among the staff", executive director Adam Farkas told AFP, as Prime Minister Theresa May prepares to take the historic step of launching the exit process this week.
"The outcome of the referendum, which will likely lead to a removal of the EBA from London, is having a major impact," said Farkas, 49, a Hungarian who has headed the EBA since 2011.
Britons voted in June to quit the EU bloc in a referendum that sent shockwaves across the globe and prompted several banks to announce plans to move jobs from London to continental Europe.
Media reports suggest that cities including Amsterdam, Dublin, Frankfurt, Paris and Vienna could be trying to woo the EBA away.
"We have seen really wide interest from European capitals, and even not only from capitals but other cities as well, who expressed their desire or intention to host us," Farkas said.
There are "quite a number of cities in the picture".
The EBA is perhaps best known for its regular stress tests on the EU's financial sector, which have become a vital focus for investors and regulators in the wake of the global financial crisis.
The EBA's London home -- in one of the city's tallest skyscrapers -- is enshrined in EU law, so moving will require legislative action.
"We do not have a formal role in deciding this," Farkas said.
"If we see some sort of shortlist emerging... we would of course consult the staff and seek for their views."
"We have not done so until now because it would probably be too open-ended and not very conclusive -- but we engage with the staff very actively."
Farkas said being in London was "very natural" for the EBA but emphasised that the organisation would rather have an early decision that would remove uncertainty and provide a longer transition period.
A state of limbo is also the case for the European Medicines Agency (EMA) and its London staff of 900, including pharmaceutical experts, biologists and doctors from every corner of Europe.
Asked what the personal impact had been of Britain's referendum to leave the EU, Farkas said: "Of course Brexit... caused a lot of anxiety among the staff", who must decide whether they will try to stay in London or leave for an as-yet-unknown city.