The European Union was brought into existence by what Karl Popper called “piecemeal social engineering”. A group of far-sighted statesmen, inspired by the vision of a United States of Europe, recognised the ideal could be approached only gradually, by setting limited objectives, mobilising the political will needed to achieve them and concluding treaties that required states to surrender only as much sovereignty as they could bear politically. That is how the postwar Coal and Steel Community was transformed into the EU – one step at a time, understanding that each step was incomplete and would require further steps in due course.

The EU’s architects generated the necessary political will by drawing on the memory of the second world war, the threat posed by the Soviet Union and the economic benefits of greater integration. The process fed on its own success and, as the Soviet Union crumbled, it received a powerful boost from the prospect of German reunification.

Germany saw it could be reunified only in the context of greater European unification, and it was willing to pay the price. With the Germans helping to reconcile conflicting national interests by putting a little extra on the table, European integration reached its apogée with the Maastricht treaty and the introduction of the euro.