The Financial Conduct Authority has published plans for a hard Brexit, with proposals to convert European law into British rules from next year.
The regulator published two consultations today (10 October), which included no new policy changes but consisted almost entirely in transposing European Union regulation into its own rule book.
This means recent European rule changes such as Mifid II and the General Data Protection Regulation will both become part of British law.
Most of the changes include the removal of references to EU institutions such as the European Commission and their replacement with the relevant UK equivalent.
In a small number of cases, the FCA proposed other types of changes reflecting the UK's new position outside of the EU.
Nausicaa Delfas, executive director of international at the FCA, said: "The FCA is planning to be ready for a range of scenarios.
"We are publishing two consultation papers to ensure that in the event the UK leaves the EU in March 2019 without an implementation period, we have a robust regulatory regime from day one, and to ensure a smooth transition for EEA firms and funds currently passporting into the UK.
"This is consistent with our aim to provide certainty and confidence for firms operating in the UK. We welcome engagement from across the sector, as we continue with our preparations for Brexit."
The FCA has also published a consultation on its temporary permissions regime, which will be used to allow European firms to continue operating in the UK in the event of a no-deal Brexit.
After Britain leaves the EU, the FCA will be taking over responsibility for regulating credit rating agencies and trade repositories from the European Securities & Markets Authority.
Trystan Lewis, a chartered financial planner with Griffin Wealth Management, said: "I suppose we are ideally looking for as much continuity as possible with regards to financial services, therefore if we are to have a hard Brexit I suppose retaining the previous legislation would probably be beneficial."