The point for the Brexit negotiations is simple and fundamental. No hard bargaining between the British government and the European Union on trade is necessary at all. The best policy is to have no tariff or non-tariff restrictions for imports from the EU, just as that is the best policy for imports from any country. Once the general election has given the Conservatives a large majority, the optimum approach would be for Theresa May to declare a policy of unilateral free trade and to move on. We just don’t care what restrictions the EU wants to impose on our exports to it. That would return Britain to the status of global free trade champion that it maintained from 1846 to 1932, when its living standards were among the highest in the world and well above those in the rest of Europe.

Historically, the Conservative Party has been ambiguous about free trade. It has always been the party of the aristocracy and the landed interest, and — while these might now be deemed mere relics — spokesmen for agricultural protectionism can still be found. But the pressure to abandon free trade in the early 20th century derived above all from the urge to make the British Empire more meaningful as a geopolitical entity. The turning-point in 1932 was not that Britain turned inwards against the world, but that its leaders regarded Imperial Preference (and later “Commonwealth Preferences”) as a better way of embracing the assortment of entities coloured pink in the atlas. May and her team are well-aware of the unilateral free trade option, but at least two objections are being voiced in circles close to policy-making. Perhaps surprisingly, the history remains important.

The first contends that we cannot be indifferent to the trade policy that applies in our European neighbours. It may well be that unilateral free trade is the best idea for us, assuming that we can do nothing to alter the EU’s Common External Tariff  (CET) and various other forms of EU protectionism. But should we take that assumption as given? Should we not try to influence the EU’s openness to our exports by faking a protectionist attitude in the negotiations? Should we not encourage them to lower the CET tariffs or to remove them altogether by saying that, if they don’t, the UK could enforce tariffs — perhaps high tariffs — on imports from our former EU partners?

In other words, we are really free traders and free trade is our eventual goal. But we live in a wicked and benighted world, where the EU trade negotiators are nasty and selfish, and certainly more evil and ignorant than us. In view of their shortcomings, we must goad them into taking the right course of action, which — as ever — is being open and liberal in international economic relations. So, if Britain threatens tit for tat, the EU’s negotiators are more likely to follow the right course of action, and to have minimal trade barriers against us. Indeed, if we are belligerent enough, we may even secure the full free trade with our neighbours that we wanted in the first place.

The weaknesses of this approach are its blatant intellectual dishonesty, and the danger that protectionist negotiating positions are declared and then become entrenched. If you believe that unilateral free trade is the right policy and say so, and yet you threaten tariffs against a protectionist counterparty, your position is obviously inconsistent and unpersuasive. If you secretly believe that unilateral free trade is the right policy and publicly say that you don’t believe in it, and so threaten tariffs against a protectionist counterparty, you should not be surprised if the counterparty is obdurately protectionist.