The pursuit of a single market in financial services is a little like opening the zoo cages and allowing a free-for-all. The lions will benefit more than the mice, no doubt provoking squeaks of protest but hardly roars of disapproval. Yet the European Commission is hearing both as it continues its marathon quest for a unified open market in financial services.

The big banks in London are well-placed to gain advantage from the directive on markets in financial instruments (Mifid), which comes into force in November. Yet parts of the City remain loudly hostile towards it and its Brussels authors.