We have been told for years that a virulent ‘flu pandemic is only a matter of time. Last year, the World Bank forecast it would depress the world economy by 5pc.

Well, it’s here. The outbreak of “swine” ‘flu in Mexico, where 150 people have died as I write, has been classified as a pandemic by the World Health Organization (WHO). There have been a number of cases in the US and a couple in the UK, although no deaths as yet.

With the entire world in the grip of a gathering recession/depression, this is what we don’t need. Britain is already facing a fall in GDP of around 4pc this year, and the effects of the ‘flu outbreak could push that up to depression levels (10pc fall in output from peak to trough) with massive implications for unemployment.

The City of London does have emergency plans for just such an occurrence and they are now being activated. The nation as a whole has enough antiviral drugs, such as Tamiflu, to cover half the population, but has rejected stockpiling face masks because they have to be replaced frequently and could be easily contaminated.

Already, markets are feeling the pinch, many headed south, while banks may need even more capital before this episode is over.