British politicians are so focused on the domestic consequences of Brexit that they ignore a more important strategic issue. We must confront the challenges in foreign and defence policies that we would have faced in the next decade even had we not voted to leave the EU. If Brexit is to succeed, a grand strategy is required in which these policies are regarded as essential, not as afterthoughts. It is not unlike the choice we faced in 1940.

Significant second-rank players like Britain struggle to exercise their strategic choices in a world dominated by the US and China. Brexit only raises the stakes. It could give us the buccaneering diplomatic elan we need in a high-tech, networked world, or plunge us into the nightmare of