It is possible, to put it no higher, that the tidal wave of investment into western banks from sovereign wealth funds (SWFs) could prove a serious mistake. Leave aside the immediate specifics of the debt crisis, since the SWFs insist they are in for the long term. But might the supercharged banking model have finally run out of road?

The supercharging is not in doubt. McKinsey estimates that in 2006, profits per employee in banking were a staggering 26 times higher than the average of all other industries worldwide. McKinsey takes this as a bull point. Others may differ.