The idea of a vote on the final Brexit deal is an appealing one to Remainers, says Steve Bullock. But by Christmas 2018, after acrimonious negotiations, the rest of the EU may be in no mood to give the UK a second chance. In any case, there would be no time to renegotiate before the 2019 deadline, which would mean Britain might end up leaving with no deal at all. The time to call a halt is now – while the EU is still receptive.

Like many staunch Remainers, I’ve often found myself supporting calls for a referendum, or, at the very least, a vote in Parliament on the final Brexit deal. It is an appealing thought. It gives hope that Brexit can be stopped at the last moment, between a deal being agreed and the UK’s exit from the EU. It also gives a nice clear defence to the ‘will of the people’ argument: democracy does not just happen on one day, the democratic will of the people evolves as new information comes to light, and a second enquiry as to whether the (rather narrowly) expressed will persists is reasonable.

It seems a fair plan, and, given the choice of a bad deal (all available deals are bad, as it happens), a stupidly catastrophic no-deal, or remaining, it’s reasonable to think Remain would have a very good chance of success.

A promise of what our politicians have cumbersomely termed a ‘meaningful vote’ in Parliament fulfils much the same role. Parliament is, after all, sovereign, and surely the amateurish, funny-if-it-weren’t-true Whitehall farce currently being played out will bring nothing that MPs of good conscience can willingly subject their country to.

We Remainers naturally assume that the EU27 would heave a big sigh of relief, perhaps demand an end to the rebate and some sundry opt-outs, and all would miraculously be well.

Donald Tusk’s Lennon-tinged invitation for the UK to change its mind, combined with less imaginative (geddit?) but obviously coordinated messaging from Paris and Berlin certainly points towards that. It looks as if Article 50 is legally and politically revokable, and the EU would welcome a UK change of heart. As the unpleasant reality of Brexit dawns on people, the Overton window is shifting back to a point where Vince Cable and even Newsnight commentators can admit that remaining is a real possibility. The UK just needs to do some sort of deal, then a referendum or Parliament will nix the whole appalling misadventure.

On reflection though, I don’t think this is true, as it relies on the idea that the EU27’s offer would still stand after negotiations are completed. The EU27’s messaging actually looks much more to me like an invitation to use this temporary window of opportunity before it is slammed firmly shut, and the security blinds lowered.

Imagine a ‘deal-referendum-remain’ scenario from the EU27’s point of view for a moment.

The end of September 2018 is the last point that a deal can be done and still allow the six months needed for ratification by national and regional parliaments. By that point, the UK would have put the EU27, against its will, through two-and-a-half years of very costly uncertainty. It would have tied up the EU27’s time, energy and resources through an insanely complicated negotiation. Five Member States would have had their Council Presidencies dominated by Brexit instead of their own priorities. The EU27 would have, by that time, negotiated their own arrangements for the future of the EU post-Brexit, including budgets, and new priorities. This will not have been easy, and will have required sacrifices by many Member States. EU27 businesses would have put their own responses into practice, shifting capital, production, staff and strategies. EU agencies would already have moved, or be well into the process of doing so. The EIB would have raised money on the markets to replace the lost UK capital.

Added to this the EU27, their governments, and their electorates, would have endured two-and-a-half years of insults, lies and propaganda from a UK government seemingly incapable of acting like grown-ups.

I therefore think that the idea that the UK could just call Brussels around or after Christmas 2018, tell them that they’re calling it all off, and just carry on as normal is not a serious one. EU27 electorates would just not accept welcoming back the UK after it had put them through so much for, basically, nothing.

Or take the scenario, which I consider likely, that the Government walks out of negotiations. A disorderly, no-deal Brexit would ensue. In this case, massive contingency plans would be well underway by governments and companies to mitigate the effects. EU citizens in the UK would be left in limbo in the absence of an agreement. Markets and the Euro may well have suffered shocks, and the ECB may well have used resources to mitigate them.

Having caused this level of harm for no reason other than the internal politics of the UK, what EU27 leader could go back to their capital and announce that they had agreed to ignore all of that and let the UK remain?

The situation is only a little different for the much mooted ‘meaningful vote’ in Parliament. Firstly, what would the vote be on? If it is on ratification of the agreement, the choice is “Aye” or “No”, not leave or remain. Accept the agreement, or don’t. There would be no time for Parliament to request a renegotiation. Even if there were, why would the EU27 consider a renegotiation after two years’ toil and cost? An amendment could be tabled, or a new bill even, authorising the Government to attempt to revoke the Article 50 notification. Would this Government be prepared to do this? A new election may be needed, but then we’re in the same position as after a referendum but with even less time. If Parliament rejects the deal, it is still possible that Article 50’s two year limit becomes the default and the UK slides out of the EU with no deal.

This all assumes of course that MPs would actually vote to reject a deal, and there has been little evidence so far that this would happen. The meaningful vote beloved of some looks anything but.

Lawyers including Jo Maugham and George Peretz have pointed out that Article 50 is probably legally unilaterally revokable right up to the point that the exit treaty is ratified by all. It is hard to see though how this could happen politically once negotiations are completed. In any of the scenarios described, it would be being revoked with with no more than three months to go until the two year Article 50 deadline. In practical terms, preparations would be in place on the EU27 side for the exit, and by then most parliaments would have ratified the agreement. The UK could simply slip out of the EU when the time ran out, presumably while still awaiting rulings from the ECJ. While the ECJ may rule in favour of the UK’s revocation, in the short term it would require political will on the part of the EU27 to either accept the revocation and halt the process itself, or halt the process pending the Court’s ruling. By that stage, they may rather just let Brexit happen and move on.

So the UK needs to grab this opportunity by the horns (or tusks, perhaps), and accept the offer of a rethink now, not at the end of the process. By then the opportunity may well be gone, and the idea that the UK can decide unilaterally to remain in the EU could be merely imaginary. Brexit can and should be stopped, but leaving it to the last minute to pull the plug on it would be a mistake.

This post represents the views of the author and not those of the Brexit blog, nor the LSE. It is based on a Twitter thread and discussion.

Steve Bullock worked at the UK Representation to the EU from 2010-2014 where he negotiated several EU regulations for the UK in EU Council working groups. He has also worked for the European Commission and the Department for International Development’s Europe Department.