"Clearly the finance sector is very important to the British economy but I don't think it's going to go away because the infrastructure in the City of London is just so great, it's unparalleled," Mellon told the BBC Today programme.
"And really no one wants to go to Paris or Frankfurt or indeed to Dublin," he said.
Despite fears about losing talent to other international businesses, 65 per cent of partners in London law firms believe the capital will retain its title as a leading legal hub, a new survey by MLex found.
Most lawyers surveyed echoed Mellon's sentiment of London exceptionalism, saying no other European city could rival London as Europe’s leading legal centre.
A City of London official today warned Square Mile jobs are at risk, however, Reuters reported.
Up to 10 per cent of jobs in London's financial district could be lost if the UK loses access to EU markets, Jeremy Browne, the City of London corporation's special envoy for Europe, said.
But Browne also said some EU cities could have trouble attracting London-based financial firms.
"One of the problems the French have, is that it's quite hard to make a pitch saying we want to be the home of financial services when you have spent 20 years making a virtue of being rhetorically hostile to financial services," Browne said.