Uncertainty surrounding the United Kingdom's 2020 exit from the European Union has reduced the number of Japanese firms operating in the country, leaving investors and analysts watching what trade promotion steps the London government will take as part of its post-Brexit economic policy.

Data shows that the number of Japanese companies doing business in the nation fell 12% from 2014 to 2019, a period that includes the 2016 referendum that determined the country's departure from what is now the 27-nation bloc.

Of the total 951 firms, the number of manufacturers dropped 22% and that of financial firms decreased by over a third, according to the Foreign Ministry data.