As Greece’s financial crisis rumbles onwards, it has become commonplace to argue that the roots of the problem stretch all the way back to the design of Europe’s single currency. Actually, it is worse than that. The Greek crisis is about the very basis on which European unity has been built for the last 60 years. It threatens not just the euro but the entire edifice of the European Union.

The risk for Europe now is that if the EU does not move forward politically in response to the Greek crisis, it will move backwards – and the long process of European integration could start to unravel.

The EU has always proceeded by creating economic “facts on the ground”, which were intended to trigger political effects. Ever since the 1950s this has worked admirably, as a modest coal and steel community turned into a common market and finally into a Union of 27 nations, with its own parliament, supreme court and foreign policy.