IMF has no experience of recession arriving with such ferocity | Larry Elliott

Recovery will take some time as countries will exit Covid-19 lockdown only gradually

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In 1941, Britain considered its colony of Singapore to be pretty much impregnable. But while the naval base was bristling with big guns, its defences were geared towards preventing a sea-based invasion and when the attack came it was on land, down the Malay peninsula. Britain was expecting trouble, just not from that direction.

The same fate has befallen the International Monetary Fund and the Office for Budget Responsibility, both of which have been forced to rip up their forecasts as a result of Covid-19. Both organisations knew there was potential for things to go wrong: they simply did not spot the likely cause.