The EU Customs Union (CU) was hardly a topic demanding rapt attention during the referendum campaign. Although it was never a focus of debate, it has since emerged as a bone of contention with the EU and has been deployed by “remainers” as a trump card suddenly plucked from a hat, yet another reason not to proceed with the Brexit process. At the very least, they say, we must remain within the CU or face disastrous queues at channel ports stretching back to London, a catastrophe for trade.

The proposition put by remainers is that the government must negotiate an arrangement for so called “access” to the CU – and the Single Market (SM) – or exporting businesses will not be able to trade with the EU and this will, of course, collapse the economy.

Nothing could be further from the truth and those who promulgate these views, rather than promoting the manifest and significant opportunities presented by Brexit, especially those so close to the issues that they have EU pensions (the likes of Nick Clegg and Lord Mandelson) must either be “knaves or fools”. They must know first of all, that we will not have left the EU unless we leave the SM and the CU. Membership of these would require the UK to continue to accept laws made in Brussels affecting large parts of our lives.

It would necessitate the adjudication on these laws by the European Court of Justice (ECJ). It would require the continuation of the free movement of people, as has been made clear by the EU and Germany in particular, and therefore remove from us the control of our borders. In fact it is totally disingenuous to argue that we can leave the EU and remain members of the SM and CU, since this would undermine the very things that define a nation state; the sovereignty of Parliament, the jurisdiction of our courts and the control of our borders, the very things that 2/3rds of the UK (and 3/4 of England and Wales) constituencies voted for.

As far as “access” is concerned, everyone has “access” to the EU market. Trade takes place between businesses and between individuals and there is plenty of it with or without an EU free trade arrangement (FTA), or any agreements on “access”. Vast amounts of trade takes place between the EU and the USA and also with China and yet neither are members of the SM or CU and neither have a FTA with the EU. In fact all the real benefits of Brexit have far more significance than the preservation of “access” or the creation of an FTA and we should give away none of these in order to achieve what would be simply a poorer version of the arrangements which we have now.

It is important to recognise that there are existing customs rules and documentation arrangements which apply to trade all around the world, arrangements which the UK already operate, as do EU member states. Any mendacious activity by the EU would be in contravention of international agreements and as the recent report on the CU, produced by Leave means Leave, makes clear the challenge of negotiating and recasting our customs arrangements is merely an administrative one.

It needs to be taken seriously. Work needs to start now, not as part of uncertain (and unnecessary) transitional arrangements. The consequences of not doing so will be as irksome to major EU states as to the UK. It is on administrative arrangements with the EU, which the UK government should concentrate its efforts during the negotiations; the CU, “Open Skies”, equivalence, visa and residency arrangements. Members should certainly not spend a moment of time and resource on fruitless conversations about an FTA but instead devote resources to being ready to crystallise the real benefits of Brexit, most of which are within our gift once we leave the SM and CU.

John Longworth is co-Chair of Leave Means Leave