Level playing fields are great, particularly when they are sloped in your favour. Jamie Dimon, the unofficial spokesman-in-chief for Wall Street, was back on fine form this month when he slammed US proposals to impose a leverage ratio of as much as 6% on big banks, double the ratio required under Basel III.

The problem, he said, was that "one of the things that Basel and all this stuff is supposed to do is harmonise global rules. This is clearly no longer harmonisation. We have one part of the world that's talking about two times what another part of the world is talking about".