On any comparison, the amount of taxpayers’ money put at risk in the authorities’ plan to rescue the UK banking sector is eye-watering.

Taxpayers are taking risks that in normal times would be thought imprudent and there is the potential for the measured level of public sector debt to explode. But these are extraordinary times and as Mervyn King, Bank of England governor, said in a statement Wednesday morning, the measures are “a necessary condition for regenerating confidence in the financial system”.