Europe can be a confusing place. Germany and France have been marching in step towards something resembling European economic government. They are at missiles drawn when it comes to Muammer Gaddafi. Britain has joined France at the head of the European coalition enforcing the Libyan no-fly zone. Yet David Cameron insists on leaving the room when talk turns to Europe’s single currency.

This curious triangular geometry was on display the other day at the summit of European Union leaders in Brussels. In matters economic, Germany is the pivotal power. Angela Merkel all but dictated the terms of the financial stability mechanism designed to underpin the euro. France has decided it prefers a German euro to no euro at all.

Mr Cameron has decided that even to sit at the same table with eurozone members would somehow taint his commitment to keeping the pound. Such is his Tory party’s neuralgia, the prime minister said he he would leave an empty chair when leaders of a new euro pact meet in future to discuss closer integration.