Inventing new taxes on banks is the latest political pastime in Europe and the US. A two-basis-point Tobin tax on trading, a 15-basis-point financial responsibility tax on covered liabilities, a 50% bonus tax on bankers – it all looks like a just and painless way to raise much needed revenue and to tamp down public bailout rage.

No doubt, there are good reasons for looking to the sector that precipitated much of the economic calamity for funds to repair the damage. Discouraging future reckless behaviour is the best of them.