As night fell over parliament on 13 March, pro-Remain MPs walked disconsolately to their offices. The House of Commons had just passed – unamended – what the Labour peer David Lea called “the shortest suicide note in history”: the 137-word Article 50 bill. Theresa May had been gifted the right to trigger Brexit without any preconditions. Even the spectre of another Scottish referendum was not enough to change the result.

Such an outcome was not inevitable. Though Remain lost in the country, it won by a landslide among parliamentarians. More than two-thirds of MPs voted for EU membership on 23 June 2016. Ever since the referendum, the possibility that the Commons could thwart Brexit, or at least soften it, had loomed.

When the Supreme Court ruled that Article 50 could not be moved without MPs’ approval, Remainers hoped to use parliamentary sovereignty to their advantage. The government’s working majority of 17 was vulnerable to a small Conservative rebellion. But it is the Leavers who have benefited. “It’s backfired on them [the Remainers],” the Tory MP Bill Cash told me of the judicial ruling.

Only two Conservatives voted in favour of an amendment guaranteeing EU citizens’ rights, while none supported giving MPs a “meaningful vote” on the outcome of the Brexit negotiations (11 others rebelled by abstaining). Labour MPs believe that what one called their “toxic leadership” has made Tories reluctant to ally with them. Brexiteers suggest that the Remainers, many of them unaccustomed to rebellion, lack the guile and the tenacity to torment Theresa May as they did David Cameron. “Stirring up trouble is a craft,” one said.

Though the Remainers were strong in number, they were divided in spirit. Since the referendum, they have been torn between those who want to halt Brexit immediately (such as Ken Clarke), those who want a second referendum to allow the voters to do so (such as the Liberal Democrats and Tony Blair) and those who accept EU withdrawal but wish to retain single market membership (such as Labour’s Chuka Umunna and Anna Soubry of the Conservatives).

On the Tory side, some opposed Brexit in the hope of advancement under David Cameron and George Osborne – a wager that did not pay off. Two-thirds, a former minister told me, were Leavers “in their hearts”. Others, such as May, accepted the referendum result on the grounds of democracy. Contrary to some expectations, public opinion has not turned since the vote. A reliable majority of people are of the view that Britain must depart the EU. The economy’s unexpected resilience has made many sceptical of apocalyptic forecasts.

May has long signalled that she intends to take Britain not merely out the EU but out of the single market and the customs union. The Prime Minister, who told George Osborne to get to know his party better when she sacked him, recognised that Tory Brexiteers would accept nothing less. The Conservative right, which some Cameroons believed had been vanquished, is now one of the most powerful factions in British political history.

May’s unremitting stance has given the SNP the ideal pretext for a second referendum. No 10 has rejected Nicola Sturgeon’s demand for a vote between autumn 2018 and spring 2019 (which would force May to fight on two fronts as she negotiates Brexit) but has not ruled out conceding one at a later date.

The entanglement of the Scottish Question with EU withdrawal has strengthened the Remainers. The softer the Brexit, they will argue, the greater the chance of preserving the Union. It is untenable, they warn, for the government to urge Scotland not to leave its biggest export market as the UK does just that.

After the triggering of Article 50, the debate will move from whether Brexit should happen to how it should happen. No longer will the Remainers be easily cast as undemocratic traitors. “People are not going to feel inhibited,” a Labour MP told me.

Yet both May and the EU-27 are intent on a “hard Brexit”. The former is determined to secure control of immigration, while the latter have repeatedly stated that the “four freedoms” (movement of goods, capital, people and services) are indivisible.

Though parliament is marginal to the negotiations, there will be multiple opportunities to obstruct the government. As many as 13 bills could be required to determine Britain’s post-EU policy arrangements in areas such as immigration, tax and trade. MPs also reserve the option of voting down Budgets in protest. Yet as long as May appears unassailable, in the face of Labour’s feebleness, most believe that she will prevail. As John Major and David Cameron learned to their cost, Tory MPs are most rebellious when their leaders are weakest. The prerequisite for a softer Brexit is a stronger opposition.