Getting ahead in global finance after Brexit needs sustained British government impetus, the City of London's policy chief said on Wednesday, adding that COVID-19 may be masking some of the impact of the country leaving the EU.

The U.K.'s financial sector lost most of its access to the European Union — which had been its single biggest export customer — after completing its exit from the bloc a year ago.

While it has adapted smoothly to Brexit, the full implications were still working their way through, said Catherine McGuinness, whose five-year term as policy chief for London's financial district, known as the "Square Mile," ends in May.