These issues are not new. Sir Robert Peel, when announcing the repeal of the Corn Laws in the House of Commons in 1846, remarked that the government should not “resume the policy which . . . we have found most inconvenient, namely the haggling with foreign countries about reciprocal concessions, instead of taking that independent course which we believe to be conducive to our own interests . . . [L]et us trust that our example, with the proof of practical benefits we derive from it, will at no remote period insure the adoption of the principles on which we have acted . . . Let, therefore, our commerce be as free as our institutions. Let us proclaim commerce free, and nation after nation will follow our example.”

It has to be admitted that the early announcement of unilateral free trade might appear quixotic. There is no guarantee that the remaining 27 EU member states would respond with equal generosity and open-mindedness. The EU might retain the current tariff levels in the CET, including such monstrosities as the 74 per cent on milk and the 55 per cent on canned peaches. Would this not be unfair on some of our producers, including (needless to say) the farming industry?

The answer is to insist that the lessons of history and geography are the lessons of history and geography, and that free trade works. If the EU were to retain the CET in its entirety after Brexit as the UK adopts a free trade regime, the long-run losers would be member states of the  increasingly protectionist EU. In the UK a case for transitional relief for particularly hard-hit sectors of the economy (including farming) might be pressed and the taxpayer might cough up to help them. But any such relief should be time-limited. If British farms cannot produce milk that is competitive at the world price, the dairy industry must close. Hard luck, but the UK no longer makes horse-drawn carriages and steam engines, and life goes on.

The second rebuttal of unilateral free trade is that it is too purist. The argument turns on the UK’s inability to negotiate trade deals on its own as long as it has been an EU member. Allegedly, we have been missing out. When free from EU constraints, and with our own representation once more at the World Trade Organisation, the UK should reach bilateral trade deals with the USA, China, Australia, Canada and so on. According to this school of thought, a multiplicity of special country-to-country deals is better than the UK’s once-for-all announcement that it has chosen free trade.

It is striking that the special-deal enthusiasts often cite the USA and the big Commonwealth countries as the UK’s most attractive associates, in the reasonable belief that strong links with them resonate well with the British public. The history, and the language and cultural ties, still matter. However, just as Imperial Preference broke with the UK’s tradition of free trade in the 1930s, so the special-dealers risk betraying free trade in the 21st century. Properly understood, a free-trading nation has zero tariffs for all products from all countries, and by definition does not discriminate between trade partners. So it has no need for any special deals. All too frequently, real-world “free trade deals” are not that at all, but specify preferential rates and arrangements of some sort, sometimes introduced to placate lobbying by a powerful interest group.