One of the more curious aspects of financial reform over the past few years is that the same banks whose complex risk management models so conspicuously failed in the run-up to the crisis should be allowed to use their own models to work out how much capital they need to avoid getting into trouble again.

And one reason why investment banks are struggling to get a fix on the horizon is that international regulators seem to be coming round to the view that allowing some recovering alcoholics to monitor their own abstinence isn't such a good idea after all.