Centre for European Reform

"We have a problem that some member-states are more constrained fiscally, and some member-states are further away from the military threats, so have much less incentive to pull their weight," said Sander Tordoir, chief economist at the Centre for European Reform. "Solving it with common borrowing allows you to provide common security for all."

Among the ideas being discussed is expanding the JEF to include Poland and Ukraine, which could provide a “deterrent presence in Ukraine through frequent exercises and the provision of air support,” according to a recent article by Ian Bond, deputy director of the Centre for European Reform.

At least, though, France seems to have “learned the lesson” that it needs “a credible, slow, fiscal tightening”, said economist John Springford of the Centre for European Reform. Germany, which needs tax and labour market reforms and public investment to raise spending, has yet to make that step, he said.

The new trading rules it has pledged to negotiate with the EU will do little to offset the economic damage caused by Brexit, according to analysis carried out by the Centre for European Reform (CER).John Springford, an associate fellow at the CER, estimates that a “reset of the relationship” of the sort Labour set out in its election manifesto, combined with the demands the EU is making in return, will raise economic activity in the UK by between 0.3% and 0.7% in the long run.