If WTO terms or existing EU preferential deals are not good enough for the UK in major third country markets, they can’t be good enough for trade with our largest market.

You cannot simultaneously argue that it is perfectly fine to leave a deep free trade agreement with easily our largest export and import market for the next generation, and trade on WTO terms because that is how we and others trade with everyone else…

….AND argue that it is imperative we get out of the EU in order that we can strike preferential trade deals with large parts of the rest of the world, because the existing terms on which we trade with the rest of the world are intolerable.

If moving beyond WTO terms with major markets represents a major step FORWARD in liberalising trade, then deliberately moving back to WTO terms from an existing deep preferential agreement – which is what the Single Market is – represents a major step BACKWARD to less free trade. You really can’t have it both ways.

Though obviously many can and do try to argue that black is white and vice versa. But it is well beyond incoherent.

It is fine and legitimate to argue that the UK should aim at a global lattice work of bilateral and plurilateral free trade deals. This is especially true in the current absence of any ability to drive forward major multilateral trade liberalisation, at a time when the US has turned inwards, and may indeed be setting about deliberalising trade, undermining the World Trade Organisation..

It is equally legitimate to argue that you only want free trade deals which stop well short of the intrusion on national sovereignty which Single Market harmonisation and mutual recognition via supranational legislation, adjudication and enforcement entails.

As long as one also recognises that all trade deals inevitable erode and trammel one’s sovereignty to some degree – often to a significant degree.

Binding international commitments to opening each other’s markets – on goods, services, government procurement, whatever – seriously limit one’s capacity to regulate sectors of the economy as one might ideally see fit.

Genuinely free global trade actually seriously trammels national sovereignty. This should be obvious to everyone – it is not news.

Possibly the greatest reason to be a passionate free trader is to curtails the ability of myopic politicians to erect barriers to commerce in the name of sovereignty and national preference against non-national producers.

This is why our current debate on sovereignty and “taking back control” is often so bizarre. It is comical listening to Right wing populist politicians claiming they are avid free traders and simultaneously saying that one of the purposes of taking back control is to be able to rig domestic markets / competitions in favour of British suppliers / producers.

Protectionism is always someone else’s sin, of course.

And the Tory Party has been through these – decades-long – spasms before. Joseph Chamberlain’s Tariff Reform and Imperial Preference campaign, as loudly pious, nationalist and messianic as many today, led all the way through to his son Neville’s protectionist legislation of the early 1930s which helped worsen a post financial crisis economy. Sound familiar?

A post Brexit Britain which is committed to openness and free trade will need first of all to run hard to stand still, as 2/3 of UK exports are currently either to the EU or to countries with whom the EU has a preferential trade deal, which we shall have first to try and roll over.

Market access into the EU WILL worsen, whatever post exit deal we eventually strike. And the quantum by which our trade flows with the EU will diminish – and that impacts immediately – will outweigh the economic impact of greater market opening which we have to aim to achieve over time in other markets, where the impact will not be immediate but incremental.

As the country debates its future trade policy in the next stage of negotiations both with the EU and with other sizeable markets it needs honesty from politicians that trade agreements take a long time.

That even if every one we aspire to were completed, this will have a really very modest impact on overall UK economic performance.

And that every version of Brexit involves a worsening of the UK’s trade position and a loss of market access to its largest market. As we strive to limit the extent of that worsening, public debate will have to be serious about what the real trade-offs are. Because the EU will be quite brutal in teaching us them.

Meanwhile, before we have even left, we have seen, in the last 2 ½ years, the most anaemic boost to UK net trade triggered by ANY major sterling devaluation since World War 2. For politicians not completely blinded by their own rhetoric, the warning signs for the UK economy as we worsen our trade terms with the Continent are there to see. Again, public debate needs to be based on the realities, not on fantasy. Or the reality will soon catch up with us.