Whatever Westminster’s failings, there is a comforting assumption that it rises to the challenge of the big occasion. As the culminating act in regaining full national sovereignty from the European Union, Wednesday’s passage of the EU (Future Relationship) Bill was a historic moment, comparable to the second reading of the European Communities Act that on 17 February 1972 passed with a majority of eight votes after three days of heated debate.

That is where the comparison ends. Neither for drama, potency of oratory nor quality of scrutiny did this closing of the European account compare to the parliamentary occasion that first brought it into being.

How could it? Boris Johnson’s brinkmanship has paid off, securing a deal on terms that seemed scarcely possible only days before its Christmas Eve breakthrough. The strategy succeeded as a negotiating ploy with Brussels. It did likewise as a means of limiting the role of MPs in scrutinising what emerged.

Scarcely 24 hours will separate the bill passing all its parliamentary stages and the end of EU law having effect in the UK at 11pm on New Year’s Eve. That is, by any measure, cutting it fine. Consequently, MPs only had five hours to debate an 85 page bill published the previous day to ratify the 1,259 page trade and cooperation agreement announced on Christmas Eve. And unlike in February 1972, the government’s ability to prevail was never in doubt. This time the majority was not eight, but 448.

Limiting backbench contributions to four (later three) minutes reduced most speeches to simplicities. For those Labour MPs following their leader’s instruction to vote with the government it was, time and again, interchangeably a “bad deal” and a “thin deal” but also “the least bad of the options” and the only alternative to no deal. It being a treaty primarily concerned with the free market for goods rather than services, Labour MPs expressed new-found concern for our important financial services, but without demonstrating any real sense of what those concerns could mean in practice. “Equivalence” and “passporting rights” were mentioned but not in a way that suggested the speakers had a grasp of what was involved or where the debate had got to with them. It was a haziness they shared with the prime minister, who deflected all service sector questions put to him.

This was not a day for details, even if it should have been. After four-and-a-half years of often brutal dispute over how – or if – the result of the 2016 referendum would be honoured, the overwhelming emotion in the Commons was one of relief that the agony was seemingly over.

To this there were a few dissenters. The Westminster leaders of the SNP and Plaid Cymru were in no mood to drop cudgels and the Greens’ leader, Caroline Lucas, launched via video link into a splenetic attack on what she damned as the “hardest of Brexit deals for which there is no mandate” achieved “on the back of the most cynical, toxic and mendacious campaign ever fought in the country.” On the second reading division, 36 Labour MPs defied their leader by abstaining and one, Bell Ribeiro-Addy, voted against (currently an independent, Jeremy Corbyn, abstained). The common theme among these rebels was not Europhilia but the Labour left’s disdain for Keir Starmer. None of the three Labour frontbenchers who resigned (Helen Hayes, Tonia Antoniazzi, and Florence Eshalomi) will be especially missed by their leader. In terms of damage limitation, it was not such a bad day for Sir Keir.

It was an unequivocally better day for the party in power. Not a single Conservative MP voted against the bill, a remarkable conclusion for an issue that has so long been the primary mark of division within the party. The emphatic conclusion of the ERG’s legal advisory committee, chaired by Sir Bill Cash, that the deal restored national sovereignty removed any likelihood of a damaging rebellion by Conservative eurosceptics. Among the latter, only Sir John Redwood and the former secretary of state for Northern Ireland, Owen Paterson, abstained. Both were concerned about the fisheries deal and, particularly, the damage done by the withdrawal agreement to Northern Ireland’s place within the UK.

The injury from that earlier agreement was the reason for the DUP’s decision to vote against the bill. As Sammy Wilson put it, the continuation of the European Court of Justice’s jurisdiction in the province and the bureaucratic barriers created between it and the British mainland meant Northern Ireland was excluded from the trade deal’s benefits: “GB companies are indicating they will no longer supply to Northern Ireland.” The DUP was voting against the trade deal not in “any common cause with the petulant Remainers,” Wilson maintained, but “because we are disappointed Brexiteers. We are people who believe the United Kingdom should leave, and leave as a whole.”

The ERG’s chairman, Mark Francois, had reason to be cheerful, announcing, “the battle for Brexit is over. We won.” And working backwards from today, future historians may conclude that this result was inevitable, that the UK and EU were never natural bedfellows and their parting on the terms achieved in 2020 was bound to happen.

the overwhelming emotion in the Commons was one of relief that the agony was seemingly over

Inevitability is historical scholarship at its sloppiest. Far from inevitable, the terms in which the UK has regained its sovereignty were open to question until the day before Christmas.

Would there even have been a referendum if in the 2015 general election a few marginal seats that swung to the Conservatives had not done so, allowing Nick Clegg to continue as deputy-prime minister with an effective veto on the “In/Out” referendum that he had previously claimed to want?

Three years after the referendum result, the prospects for it being re-run in the hope of reversing the original verdict remained high. Even more likely was Brexit-in-name-only, as represented by the deal Ollie Robbins negotiated with Michel Barnier and which Theresa May almost secured, at the third time of asking.

May’s super-soft Brexit (with the UK remaining effectively within the EU customs union and its regulatory orbit) failed because of the obstinacy of 28 ‘Spartans’ of the ERG. Without such risky bloody-mindedness – as unbendable principles may also be described – the effective return of sovereignty from the EU would not have been achieved. Wednesday 30 December was these Spartans’ victory, as much as it was also that of the prime minister who finally secured it.

But there is another group who made it possible – the parliamentary Labour Party. Sir Keir Starmer has ended-up voting for a trade deal that restores far more sovereignty to the UK than he could have conceded had he not, as Labour’s Exiting-EU spokesman, in early 2019 matched the Spartans’ obstinacy with its Remain equivalent.

During Wednesday’s debate, Starmer maintained that whilst he was reluctantly voting for the European Union (Future Relationship) bill, what he really had wanted was a much better deal (in other words, one with greater alignment to EU regulation). It was a conceit neatly shot down in a pithy riposte from Theresa May. “He said he wanted a better deal” chided the former prime minister, who has acute recall for those who crossed her: “He had the opportunity in early 2019 when there was the opportunity of a better deal on the table. And he voted against it.”

Arise (again) Sir Keir Starmer – the unintentional mastermind of Brexit-in-reality-fully.