The European Union's markets regulator has set out a list of do's and don'ts for UK firms wanting to set up an EU presence after Brexit, and the national regulators who will have to oversee them.

The European Securities and Markets Authority, known as Esma, said financial firms must not be able to sidestep Brexit by setting up "letter box entities" in Europe. It also wants to prevent national financial regulators watering down EU rules in order to attract businesses.