The penny has dropped in London and New York that banks are not reliable sources of tax revenues. Losses from the credit crisis mean that some investment banks may not pay taxes, as Michael Bloomberg, mayor of New York, gloomily phrases it, "for years".

The most spectacular example is Merrill Lynch, which has booked $29bn of losses from its rash involvement in trading collateralised debt obligations, in London. Although many of the deals in question were struck by bankers in New York, Merrill booked them to its London subsidiary.