The UK political commentariat are a lazy bunch. Brexit is one of their biggest topics in decades – a bonanza that any amateur can pitch in on – yet remarkably few have got to grips with the key texts. If they had, they would realise Brexit is at that stage of the chess game where the result is already a foregone conclusion. Brexit is going to happen.

Some more enlightened MPs saw this a while ago. Would Anna Soubry have resigned from the Conservative Party if she thought Remain or BRINO (Brexit In Name Only) were on the cards? Would Jeremy Corbyn offer a second referendum to his diehard Remainers if he thought there was any probability of Remain? You can hear the anguish of opportunists who placed their chips on defending BRINO from space as they realise they will end up on the wrong side of history.

So why should we be so certain that Brexit will triumph?

You would be right to be sceptical. We have a Remain Prime Minister, a Remain Civil Service, a Remain Cabinet, a Remain state broadcaster, a Remain undergrowth of NGOs, an increasingly bitter and unpleasant spectrum of Remain campaign organisations and, of course, a Remain Parliament. But no need to panic. They are all going to lose.

So here are the key facts and texts:

Article 50 & The European Union (Notification of Withdrawal) Act 2017

This legislation passed by Parliament by a massive majority authorised the Prime Minister to notify the EU under Article 50 (TEU) of the UK’s intention to leave the EU. The UK under EU law will leave the EU on 29th March 2019 at 11pm unless the UK requests – and gains EU approval for – an extension.

The European Union (Withdrawal) Act (EWA)

The EWA, again passed by a large majority, is the domestic counterpart to the Article 50 notification. This Act sets 29th March as the exit day in UK domestic law. Exit day can only be changed by a Statutory Instrument that would have to go through the Commons and the Lords (s.20 EWA).

The EWA (s.13) also sets out the procedure for ratification of a Withdrawal Agreement:

It requires approval in the Commons;

It requires an Act of Parliament to implement it. The so-called Withdrawal and Implementation Act – the WAIB – would need to get through both the Commons and Lords.

The Cooper Amendment F passed on 27th February

This amendment – supposed to be a copy of the Prime Minister’s commitment to further votes – was added to a non-binding Commons motion that the Prime Minister has agreed to be bound by. It allows for a further ‘meaningful vote’ on a Withdrawal Agreement followed by (a logically flawed) vote to accept or rule out ‘no deal’ and lastly, if ‘no deal’ is ruled out, a vote to seek an extension to Article 50 to Remain in the EU.

These texts taken together make the life of a pro-Remain insurgency very difficult, even if that insurgency were headed by the Prime Minister.

Imagine yourself as a bitter Remainer…

Imagine you were tasked with trying to overturn Brexit. If that is too difficult, study the plans put forward by one of the authors of the Chequers Proposal/Withdrawal Agreement/Political Declaration, in a bar in Brussels – it’s much the same thing. You have some immediate and catastrophic problems.

Requirements for a straight Remain without ever leaving

Ultimately, unless you are a highly committed enemy of democracy, you would require a second referendum to overturn the first. Assuming the voters can be instructed to behave a second time, you would also require an Article 50 extension to gain the time to conduct the poll. This would require the following basic requirements:

Parliamentary time to push a Bill through the Commons and Lords to empower or force the Prime Minister to seek an extension of at least nine months. This could be done in the Commons maybe via a rebel amendment to the 12th March motion to take control of the Order Paper followed by speedy readings of the latest iteration of the Cooper/Boles Bill. Gaining Commons time would be difficult enough but the Lords would present a similar problem. Attempting this Bill would be even more difficult to attempt if the WA had already passed, so diehard Remainers would end up having to vote against the WA (see below). All EU states would have to agree the extension to a specific date for a specific purpose. This is unlikely to be straight forward or cheap. Parliament would have to vote to accept the specific date and change the ‘exit date’ in the EWA. Parliament would have to pass a Referendum Bill and hold the referendum before you have timed out. Negotiate with the EU to turn the ‘extension’ into a permanent say – no doubt involving Parliament endorsing new terms.

Requirements for BRINO – keeping the option of Remain open

The current Withdrawal Agreement would lead to a customs union and dynamic regulatory alignment, keeping UK laws in harmony with the EU. Some more far-sighted Remainers might think this vassal status would be a good springboard to re-join the EU. If we accept all the EU rule book, why not go that further step and have a say on how they are drafted – i.e. membership?

This plan requires the adoption of a Withdrawal Agreement and Political Declaration (WA&PD) deal built on a permanent backstop that leads with all certainty to a customs union. This agreement is the one that Parliament rejected.

In order to push through the WA&PD, the Government has a problem. The issue that MPs have taken up most vocally – the lack of an exit from the backstop – is the part the Government most requires to deliver BRINO. So how do they get their deal through Parliament? This is set out, following the Government’s acceptance of the Cooper Amendment F:

Request a change in the WA from the EU27 to give what appears to be (but isn’t) a legally-binding exit from the backstop. By 12th March hold a new vote to approve the WA&PD and overturn the previous defeat by a majority of 230.

In order to pressurise MPs into voting for the WA&PD the Government will seek to deploy the threat inherent in the second two parts of the Cooper Amendment F: if the WA is voted down, the Government (if it decided to acquiesce in Remain and follow the motion) would then table a motion to endorse leaving without a deal which, if defeated, would require a further motion on 14th March to instruct the Prime Minister to seek an extension.

Is threatening an Article 50 extension a credible threat?

It is of course gratifying that even Remainers acknowledge that remaining in the EU is a threat to be wielded. But it’s not a credible threat. If MPs are minded to vote against the Withdrawal Agreement they are not voting to stay in the EU. So, what would happen?

If the Commons defeats the Withdrawal Agreement again before 12th March, they may be presented with a vote on ‘no deal’. If for the sake of argument the Commons votes against ‘no deal’ and then votes on 14th March to request the Prime Minister to request an extension of Article 50, they are too late – there would be only 17 days left. In that time they would need:

The Prime Minister to seek approval of the EU27 to a ‘short, limited extension’ for an unknown period for an unknown purpose. That would not be favourably received by the EU27. There would also be a threat of legal action if the request were not endorsed by a full Act of Parliament. Assuming an extension could be agreed, the Government would also need to move a Statutory Instrument in both the Commons and Lords to change the exit date in the EWA to the one agreed with the EU27 – but that would only buy a short extension before all the same issues re-emerge. Nothing would really have changed. If you do not want the Withdrawal Agreement, a small probability of a short delay is not a credible threat.

In any event, if the WA does get through there remains the need for the Government to push the complex WAIB through the Lords and Commons pre-29th March or be timed out.

So far, so technical. But this is a discussion in isolation to the world outside of Westminster. These decisions have electoral consequences for political parties.

Firstly, the cause of Remain requires the Prime Minister to actively promote it or at least acquiesce in the face of Remain MPs and Ministers. If the Prime Minister wants to leave, we leave.

There is no need for her to champion Remain, accept motions or give parliamentary time to Remainers – that is a political choice. It’s a choice that will have dramatic political consequences for the Conservative Party if the UK is still in the EU (or has BRINO) after 29th March. In that circumstance, the DUP might depart, if they had not already and the Government would either fall or require a new Prime Minister who had not supported the WA. That is not something a Conservative Prime Minister would want a as legacy – the balance of threat is very much in favour of Leave.

Secondly, the reputation of Parliament generally would take a hit. The EU issue would become further polarised to an extent that even committed Remainers (and EU partners) would realise that the UK’s continued membership would be politically unstable and counterproductive.

This brings us to the obvious conclusion that Brexit cannot be stopped.

If the EU does agree a replacement to the backstop (a scenario made less likely now the PM has floated an extension) then the WA may yet get through the Commons, and shorn of its permanence, a new PM could then build a genuine free trade Brexit deal.

If the Government brings back the same deal without an exit to the backstop, it will be defeated. If it is defeated, there will be no second referendum or prolonged stay in the EU. The UK will leave.

In short, don’t panic: if MPs hold their nerve, we are leaving the EU on 29th March without a permanent backstop.