One year on, the political weather has changed and suddenly a once unthinkable question can be asked: might Brexit be stopped?

The obvious shift is in the power of a government whose animating mission was meant to be British departure from the European Union. Put simply, Theresa May sought a mandate for hard Brexit and didn’t get it. That leaves the forces of leave weakened, and remain emboldened.

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It also shreds the boasts that formed the basis of May’s premiership: that she’d be able to get a great deal for Britain. Too weak to negotiate a deal with 10 MPs from the Democratic Unionist party, what hope does she have against 27 sovereign European nations? In a taste of humiliations to come, her opening offer on the rights of EU nationals in Britain was dismissed out of hand. But that is only the most obvious change.

The deeper, if less tangible, shift is that the case for leave is collapsing before our eyes. Its central, winning claim – that exit would bring £350m a week for the NHS – lives on now only as a punchline and case study in Trumpian dishonesty. It will endure as a short, sharp argument for why Boris Johnson must never be allowed to become prime minister, and may well stand between him and his party’s leadership. But most of all, it encapsulates the notion that leave won last year on a false prospectus. Johnson and the others promised a magical cake that could be simultaneously gobbled up and left untouched. Leave’s other big pledge was a fall in migration, but this week’s UK population figures, with a 5 million increase in a decade, confirm that EU migration has only ever been part of that story. Meanwhile, farmers and hospital managers alike warn of dire consequences if they cannot bring in essential workers from the continent. Already the numbers, whether of fruit-pickers or nurses, are in steep decline.

After 12 months, the economic damage is beginning to show too. The pound has lost 14% of its value against the euro; the governor of the Bank of England says “weaker real income growth” cannot be prevented. Inflation is rising. Brexit has made Britons poorer.

It’s noticeable that leavers no longer say that Brexit will deliver us to a sunny land of sovereignty and independence. Their talk is more defensive now; they know that fears of job losses and shrunken wages cannot be soothed by abstract nouns. These days the leavers’ stance is captured by the strained voice of Iain Duncan Smith insisting that things won’t be as bad as the gloom-mongers say.

More revealing still is the Brexiteers’ reliance on a kind of fatalistic compulsion. We have to go through with it, they say, we have no choice. Leave was “the people’s will”, so we’d better get our heads down and trudge through a process as hard as defeating the Nazis because it’s too late to back out.

But is it? That depends on four key sets of players. The first are our European neighbours. The continent’s emerging power couple, Emmanuel Macron and Angela Merkel, are chipper these days, pumped up by support at home and the fact that the eurozone is now economically outperforming Brexit Britain. They are not needy for our re-embrace.

What’s more, were Britain to seek an extension of the article 50 deadline – begging for more time to negotiate our exit, maybe even hoping to push departure into the distant future – there are obstacles in the way. Permission from the 27 EU states would have to be unanimous, and with elections to the European parliament due in 2019, and the next seven-year EU budget to be agreed around the same time, they’d need clarity on whether Britain was in or out.

That said, if Britain truly changed its mind, Europeans would open their arms. Donald Tusk, president of the European council, was asked on Thursday if it was too late for Britain to stay. The EU was built on impossible dreams, he said, before turning lyrical. “You may say I’m a dreamer, but I’m not the only one.”

In other words, if we wanted to do it, we surely could. But that would require a clear, unmistakable shift in British public opinion. There is a paradox here. The economic pain Britons would surely have to feel to abandon Brexit may not be fully felt till after Brexit. And by then it would be too late.

Still, some of the economic cost could become clear in the “transition period” that now seems likely to follow formal exit in March 2019. Charles Grant of the Centre for European Reform imagines the reaction once, say, Airbus leaves the UK, along with various car companies. “If in that period, the macroeconomic truth dawns, that the trade lost is far greater than any trade gained by new agreements around the world, people might begin to think again.”

That leaves two more key players. For Brexit to be delayed or reversed, Labour would have to alter its current stance. The ambiguity of its position seemed to work on 8 June, winning support from both leavers and remainers. But the leave component of that coalition may have been exaggerated: subsequent analysis suggests only 18% of ex-Ukip voters backed Labour. The party’s biggest surge came in heavily remain areas. In other words, Labour may be able to embrace a more anti-Brexit position without paying too high an electoral price. That could, for example, be an insistence on staying in the single market.

Unless an early election sees a pro-remain Labour party win an overall majority, the Tories too will have to change if we are to wrench ourselves off the current path. It’s tempting to think the answer lies with a remainer replacing May. In fact, the Nixon-to-China principle suggests a leaver would have more room for manoeuvre.

The realistic view is that Brexit cannot be averted, it can only be softened. Grant reckons the democratic catharsis of exit might be a necessary first step: “We have to get out before we can get closer.” But even that scenario opens up all kinds of possibilities. A paper calling for a new “continental partnership” has prompted much interest in pro-European circles: it envisages a two-tier Europe, with Britain sitting in an outer tier, enjoying a form of single market membership that nevertheless allows for limits on free movement.

That may not be where we end up. It may be that we find our eventual place instead in a customs union-plus or a single market-minus. But multiple options suddenly seem possible. One upside of the current volatility in world affairs is that nothing is fixed, nothing is preordained. We are not shackled to the verdict of 12 months ago, not if we want to break free of it. If time and circumstance lead us to conclude that we are at the precipice, staring into an abyss, we can always step back. We are not passive; our fate is not sealed. We can take back control.