Alongside rising job losses, repossessions, bankruptcies and suicides, economic downturns inevitably trigger one other trend: protectionism.

Calls for tariffs, quotas and other measures that, in the short run, help to defend local jobs against foreign competition increase in volume and intensity and are often heeded.

With unemployment lines lengthening, it is particularly hard for governments to award contracts to overseas bidders when there is a home-grown option.

So even as President Bush was putting his signature this week to the latest G8 communiqué applauding open markets and free trade, his lieutenants were preparing to scotch the $35 billion deal awarded to a joint European-US consortium, giving a fresh chance to a rival 100 per cent American bid from Boeing.

With America facing its worst downturn in years and an election four months away, it was no great surprise. As growth slows across the world, protectionism is in the air and free traders are on the back foot.

Barack Obama, the US Democrat candidate, clearly sees advantages in playing the protectionist card, claiming that the North American Free Trade Agreement — which opened up US markets to Mexican and Canadian goods — has destroyed one million US jobs, as he seeks to win the blue-collar vote.

Protectionism can be a popular move, especially in tough economic times, but it is self-defeating when everyone does it. President Hoover’s decision in 1930 to slap high tariffs on imports helped to trigger tit-for-tat protectionist measures that led to the Great Depression.

Times Recommends

• Lies and cover-up at MG Rover exposed by report
• High oil prices push manufacturing costs up
• Primark founder steps down as chief executive