The liberal Leavers are peddling an illusion. On contact with the reality of Brexit, their plans will fall apart. If Britain leaves the EU, it is likely to end up poorer, less open and less innovative. Far from reclaiming its global outlook, it will become less influential and more parochial. And without Britain, all of Europe would be worse off.

Start with the economy.Even those voting Leave accept that there will be short-term damage. More important, Britain is unlikely to thrive in the longer run either. Almost half of its exports go to Europe. Access to the single market is vital for the Cityand to attract foreign direct investment. Yet to maintain that access, Britain will have to observe EU regulations, contribute to the budget and accept the freemovement of people—the very things that Leave says it must avoid. To pretend otherwise is to mislead.

Those who advocate leaving make much of the chance to trade more easily with the rest of theworld. That, too, is uncertain. Europe has dozens of trade pacts that Britain would need to replace. It would be a smaller, weaker negotiating partner. The timetable would not be under its control, and the slow, grinding history of trade liberalisation shows that mercantilists tend to have the upper hand.