Constitutions are written by the winners. That is no less true for a country such as the United Kingdom, whose constitution is largely unwritten, than it is for those founded after wars of independence or unification. It’s just that, throughout history, the winners in Britain’s case have been whatever party or political force held a majority in the House of Commons.

That means that parliamentary procedures generally favour the executive, rather than whatever the views of a majority of MPs on any given day happen to be. (Confused about the difference? Think of it like this. There is a majority for a soft Brexit in the Commons. But the will of the executive is that Theresa May’s deal gets through.) Even the speaker – who notionally surrenders his or her party affiliation – is generally chosen with one eye on preserving the governing party’s interests.

Only once in the 20th century was a speaker – Labour’s Betty Boothroyd, the first and so far only woman in the role – elected from outside the governing party. Her successor, the Labour MP Michael Martin, was championed because the Labour whips believed he would be a friend to the executive. Martin’s replacement, the formerly Conservative John Bercow, was favoured by the outgoing Brown government because of his independent streak. (A quality that governments tend to become fond of only when they suspect they are leaving office.)

Bercow was praised by Brexiteers on 13 May 2013 when he broke parliamentary precedent, allowing a motion regretting the absence of a European referendum on the government’s legislative agenda to be debated and voted on in the debate on the Queen’s Speech. He was demonised by the same group on 10 January 2019 when he broke precedent to allow Dominic Grieve, a Conservative backbench Remainer, to seek to amend the legislative timetable.

The Brexiteers’ recent anguish was real, but it ignored the undeniable fact that whoever has held a parliamentary majority has sought to use that majority to bend the rules of the game long before John Bercow was Speaker – and they will continue to do so long after he retires. Notably, though, for most of the time Bercow has been Speaker, the Conservative Party has either been in opposition or without a parliamentary majority. As May navigates the treacherous path through Brexit, it has become apparent that for the first time since 1979, the British constitution is not solely being written and interpreted by the winners. The governing party cannot always get its own way.

To find precedents for the current state of parliamentary upheaval, it is necessary to look back further, perhaps to the late 1970s. Even then, though, Labour’s period of minority government from 1974 to 1979 was not the rolling five-year crisis it is sometimes portrayed as being – among other things it found the time to introduce statutory maternity leave and to keep Britain in the European Economic Community. And it never had to pass highly contentious legislation within 60 days to prevent an economic catastrophe. Nor did it ever face a split as large or as severe as that within the Conservative Party over Brexit.

Overseeing this unprecedented time of upheaval is a prime minister marked by her refusal to compromise and her tendency to gamble (and lose). After Theresa May returned to the House of Commons on 21 January following her record-breaking defeat the week before, only to announce that her policy priorities for Brexit had not changed, Labour’s Yvette Cooper quipped that “the Prime Minister seems to be talking as if she lost by 30 votes, not 230”.

The line resonated because it spoke to a common criticism of May: that she is stubborn, dislikes dissent and refuses to co-operate with others, particularly when those others have committed the cardinal sin of belonging to a party other than the Conservatives. Yet the bigger problem, which would hold if May had been defeated by even a single vote, is that her negotiating strategy – to seek further concessions on the backstop, the “insurance policy” to avoid a hard border with Ireland – is not viable.

The central cause of Tory anxiety over the deal is that the backstop has no time limit and that the UK cannot unilaterally exit it. But an insurance policy that the insurance provider can exit at any time is no insurance policy at all. No such changes to the backstop can and will be negotiated by Brussels, but without those changes May has no hope of winning over enough Conservative or DUP MPs for her withdrawal agreement to pass the Commons. That means that the only way to avoid a no-deal exit on 29 March is for an accord to be reached that can win over at least some Labour MPs.

The cabinet is divided over whether such a move is achievable, let alone desirable. One cabinet minister believes that May can pass a deal through parliament but “only as a passenger”. May cannot put forward the only deal that could attract majority support in the Commons – which would involve the UK staying in a customs union – because it would tear her party apart. But she could, the thinking goes, accept such a deal if it arose from backbench discussions.

Not everyone in the Conservative Party agrees with this analysis. Some think that even acquiescing to such a deal in the face of parliamentary defeat would break the party in two. Others believe that a Brexit in which the UK stays in the customs union is pointless.

The belief that there is simply no form of Brexit acceptable to both parliament and the executive is one of the reasons nine ministers, three in the cabinet, have told their local party associations to prepare for an imminent general election.

It is sometimes said that there were 17 million reasons to leave the European Union, one for every pro-Brexit voter. These days, parliament often feels caught in a similar trap, as if there are 650 opinions on how far it is acceptable for MPs to seize control of policy from the executive. At one end, there is Dominic Grieve, who proposed a radical amendment to be debated alongside May’s “Plan B” on 29 January, which would have forced the government to make time for MPs to discuss a range of alternative Brexit plans. (Faced with accusations that he was mounting a “coup”, Grieve noted that the government has not granted an Opposition Day, where it allows other parties to have debating time in the House, since November.)

Government loyalists were not the only ones alarmed by Grieve’s suggestion; pro-Corbyn MPs feared that supporting it would create an uncomfortable precedent for a minority Labour government should one be elected. (Others think this argument is naive – one shadow minister told me “only an idiot” would believe that a minority Labour government would not immediately face a more assertive opposition than Theresa May does now, or that its efforts would not be cheered on by the same newspapers that denounce Bercow.)

However, a more limited motion by Yvette Cooper, backed by Labour’s Hilary Benn and Liz Kendall plus the Tory Nick Boles, among others, is highly likely to pass. It would ask the government to seek an extension to the Article 50 process if parliament has not agreed a deal by 26 February. This is more palatable to the Labour leadership, because Corbyn has repeatedly stated that he wants to avoid no deal.

There are problems, however. The goverment cannot unilaterally extend Article 50; it can only make a request to the EU27. The other EU countries would most likely agree to that request – they are not keen on a disorderly exit – but, knowing that no deal hurts Britain the most, would try to extract further concessions in exchange.

The trouble is that while a majority might be found for extending negotiations, it is not clear how constructively that extra time can be used. Delaying the time bomb does not magically create a majority for any alternative to exiting without a deal.

There is more support for reopening the referendum question on the Labour benches than for any other single Brexit outcome, but even that would struggle to command a majority of Labour MPs, let alone a majority in parliament. Dozens of Labour MPs have pledged to their constituents that they will implement Brexit and others are lifelong supporters of leaving the EU. Conservative rebels are split between those who think that a close, Norway-style relationship is an adequate way of honouring the referendum result and others who believe that the referendum result was so chimerical it can never be meaningfully honoured. The latter group thinks that the only way out is a fresh referendum, where voters can either choose Brexit with open eyes or reject it entirely.

With such deadlock, no one is in charge. The only way forward is either for parliament to overpower the government or for the government to find a more congenial parliament through a fresh general election. If neither happens, prepare for a chaotic exit, whether that comes at the end of March or the end of the year.