It was not the UK that ran/runs the world's finance, it's the tax haven of the City of London, with its overseas branches in UK territories that still runs the world's finances.
Current CT: Brexit has to happen before 2020 because otherwise City of London will be subject to EU rules that will cause current anonymities to be revealed.
Current CT: Brexit has to happen before 2020 because otherwise City of London will be subject to EU rules that will cause current anonymities to be revealed.