The prophets of gloom who argued that globalisation was doomed, in the aftermath of the outrage of September 11 2001, have so far turned out to be wrong. The onward march of global economic integration has survived financial crises, the collapse of stock market bubbles, terrorist attacks, the need for tighter security, wars, fear of disease, natural disasters and oil shocks.

The forces driving globalisation are extremely powerful. But extremely powerful is not “invincible”. The world economy retreated from openness between 1914 and the middle of the 20th century. It could do so again.