In his letter to leaders ahead of the summit, Donald Tusk, the EU Council president, said “there is presently no consensus” on this point. But a way through will be found; it always is. And what is going on in France, Denmark, Poland and the east European states, where fences are erected against the influx of migrants, should make those running the EU realise that their great ideal is facing an existential crisis. Perhaps they simply cannot see it. But they would be mad not to give Mr Cameron enough wriggle room to claim some sort of triumph on which he can campaign to stay in.