The 230-vote margin by which the Government lost the meaningful vote outstrips by a long way the three losses of 166, 161 and 140 votes suffered by the minority Labour government of Ramsay MacDonald in 1924, previously taken as the high water mark of government defeat in modern parliamentary politics.
What is more, this is not defeat on some side strand of the Government’s agenda. It is a defeat on the Government’s main project – really, its only project – and the overwhelming focus of its efforts for the past two and a half years. It is the issue with which Theresa May’s premiership has been inextricably linked.
In December, MPs found the Government in contempt of Parliament – another historic first. Gareth Johnson’s resignation on Monday this week as a Tory whip brought the total number of ministerial resignations since the 2017 General Election to 22 – 13 of those over Brexit.
That is the highest rate any recent government has suffered.
Meanwhile, last week’s decision by Speaker John Bercow to allow an MP to amend a government motion in a way that would normally be deemed impossible set a precedent that may give backbenchers greater power to affect the Government’s agenda.
The Prime Minister herself has not resigned though, another way in which this drama has departed from precedent. Her predecessors, suffering a defeat on such a central matter of policy, might well have done so.
Instead, she has laid out that if she wins the vote of no confidence, she will head back to the Commons to explore whether MPs can muster a majority for any one option.
Beyond the record-setting quality of the drama, the importance of the result is that it does not point to any consensus on the way ahead and the implications of that could be serious.
It is not as if the House of Commons resoundingly rejected one course, to accept a Plan B as a result. This vote rejects the Government’s negotiated deal but leaves all the other visions, of very different shades of plausibility, still in play.
Indeed, one reason for the size of the Government’s defeat is likely to have been that so many MPs, whether favouring renegotiation with the European Union, a second referendum, or “no deal”, felt that their preferred version stood a chance only if Plan A first went down in flames.
While they feel that chance is alive, a majority may prove elusive, even though the PM now intends the cross-party exploration of views that she had previously declined to investigate.
But if the Commons cannot agree on anything, no deal remains the default outcome on March 29, even though there is probably a majority of MPs keen to avoid it above all (and the Institute for Government has argued that the UK is not well prepared to handle the effects).
Some MPs back a second referendum and more might do so if the Commons fails to agree on anything else – yet it remains unclear whether they can find consensus on the format or whether the result would settle the question.
Labour’s prime goal is a General Election, and yet its Brexit policy, on which that would be fought, asserts that it could extract the benefits of the single market from the EU without being an EU member.
Neither device – another referendum or an election – reliably releases the Government or the country from the present limbo where nothing is advancing except the clock.
The extraordinary quality of this spectacle lies in the way that, after two and a half years, with 70-odd days to go until the UK’s automatic exit from the EU, every option which every faction has entertained in that time is, at least in theory, still in play.
True, some of the roots of this predicament lie in the nature of the 2016 referendum itself: a very close vote, where the nature of Brexit was not spelled out. Theresa May’s defenders may well say in retrospect that she was merely trying to reconcile the promises of the Leave campaign with the EU’s principle that only members should get the benefits of membership.
To jeer that she was hunting for unicorns is unfair, they will say. Given her starting constraints, she got the best deal she could have done.
That may be true – but she didn’t have to start from there.
Looking back, it is already clear that among the serious tactical mistakes (including triggering Article 50 without an agreed destination), the main one was setting her “red lines” to please Eurosceptics, without regard to whether those left room for a deal that the EU and a parliamentary majority would both support. Others included misunderstanding EU concerns, and neglecting the Irish border. The present position follows from those mistakes.
That conclusion matters because for all the historical significance of this defeat, it would be wrong to conclude that the UK’s parliamentary democracy itself is fundamentally broken and could never have coped with such a divisive question.
The UK’s government and its Parliament have arrived at an extraordinary impasse. But with the first key vote now past, there are new routes ahead to break that deadlock. Even if they break new unwanted records in the process, the Government and Parliament now have a chance to do so.