The UK Brexit debate has consistently misread the EU’s aims, and its determination to pursue them. We are now at risk of doing so over the negotiating endgame. No deal, if it happens, will be a process – not an event – managed by the EU to their negotiating advantage, just as the article 50 talks have been throughout. The difference is that a no-deal process would be much shorter and more brutal for the UK.

The Brexit debate in the UK often misses the very modern political motivations of the EU27. Yes, they are determined to defend the rules-based single market, built up through decades of compromise. But leading EU member states have a political aim closer to home; they must defeat the idea of a painless Brexit. Otherwise, they fear, the European parliament elections next June will be dominated by their own populist opponents, who will claim that they, too, can shed the obligations but keep the benefits of EU membership.

This budget may not survive the coming Brexit hurricane | Matthew d’Ancona Read more

The UK’s bruising experience in the Brexit negotiations, and the likely outcome, may have already made the point clearly enough. But if British politics remains stuck on demanding the impossible, as the EU see it, no deal can also become a process to make the message crystal clear.

Some key EU governments think that a “managed” no deal, with the worst effects mitigated for the 27 by temporary recognition of UK standards to allow, for example, direct flights to continue, would be bearable. The European commission is preparing plans along these lines. There would be emergency support for those, like Ireland, who were worst hit. And, crucially, the crisis would be short. The impact on the UK from customs delays alone would be so disastrous that London would quickly come back to the negotiating table.

In this sense it doesn’t matter whether the UK government or parliament is the blocker to a deal. For the EU, no deal is not an end state; it is the continuation of negotiation by other means.

This is not fully appreciated in the UK, where – because of the internal struggle for Conservative MPs’ votes – both sides deliberately talk about no deal in extreme, quasi-religious terms. The UK will “fall” into a dark pit of rationing and transport chaos if backbenchers defy the prime minister, or (as hard Brexiteers have it) the country will purify itself of self-doubt in a baptism of fire. Either way, no deal is depicted as a long, hard struggle.

In reality, as cabinet ministers are realising, no deal would quickly bring the UK to a halt, and destroy the government which presided over it. Blaming EU intransigence would not hold as a line for very long, with motorways gridlocked and essential supplies uncertain. Very senior customs officials compare this scenario privately to a first world war battlefield. “It will be triage,” says one; customs officers on the ground making individual decisions to wave through suffering live animals, or medicines, holding back almost everything else. The National Audit Office shows how far away the UK is from being able to cope with the realities of a third-country relationship with the EU at 11pm on 29 March.

The EU will not choose this route just to make a point. It would be painful for many member states, and particular regions – such as Calais and the surrounding Hauts-de-France – would suffer. A prolonged no deal would be disastrous for Ireland, trapped by geography. It could fracture EU unity over Brexit. But the important fact is that key EU leaders think they can take the risk, confident it would only last a matter of days before the UK had to seek a deal.

It is a huge risk. The British government would either come to terms or quickly fall. Even if the UK agreed a deal, we would be facing an unprecedented political crisis. The government would still have to get a deal through parliament, with a substantive bill, as we explain in our report “Time is running out to enact a withdrawal agreement bill”.

Approving a government motion on the withdrawal agreement is just one of two steps needed for the UK to ratify the deal. The second is the passage of primary legislation to implement the withdrawal agreement, which must receive royal assent before the Brexit deadline of 29 March.

That would happen in a mood of shock and, potentially, humiliation. A general election, even a new referendum, are possible. But so is a hung parliament or a popular rejection of the deal. In that scenario, all bets are off.

There will be more negotiating posturing before agreement is reached, and quieter fears of no deal happening by accident. The UK’s decision-makers, in government or on the backbenches, would be better placed to avoid that risk if they understood why the EU can – and will – contemplate no deal. And why they are sure that the UK cannot.

• Paul McGrade provides senior counsel at Lexington Communications. Previously, he worked at the Foreign Office, the European Commission in Brussels and the Cabinet Office as an advisor on EU treaty negotiations