The trouble with great debates is that a few dominant themes create such a cacophony that they drown out other critical questions, especially if they are complicated and long term. The Great Brexit Debate is becoming a classic example.

In our fractious post-referendum world, the political weather is being made by the fusion of two questions: do we want “hard” or “soft” Brexit (which would include access to the single market)? And, how tightly, exactly, do we want to control immigration? We hear hardly a squeak about, for example, our science and technological base and its indispensability to our future economic and industrial performance, except when the free movement (or not) of scholars and students feature in the wider immigration arguments.

Pretty well all sides in the Brexit debate agree that the success or otherwise of the dash to leave the European Union (EU) will not be knowable for 10 years or more after the final departure deal has been agreed between the United Kingdom and the 27 countries with whom we shall henceforth be on less intimate terms.