What is the single biggest danger to the long-term cohesion of the European Union? The failure of the Lisbon treaty? Another foreign policy disaster? Or a low voter turnout at this week’s election to the European parliament? I think not. The biggest danger would be the erosion of the single European market. And it may be happening.

The single market is enshrined in European law. It would take a change in the European treaties to reverse it – and this is obviously not going to happen. The single market will therefore not collapse, or be replaced by something else. The real danger is that it may wither, quietly.