How will the Tory party remember 2017? Will it be the year it lost its majority, alienated key sections of the electorate and paved the way for a Jeremy Corbyn premiership? Or the year when uncertainty about Britain’s future relationship with the European Union peaked, when debt finally began to fall and the Tory party resisted the temptation of a Corn Laws-style split? We won’t know for several years. What we can say with confidence is that Brexit will prove key to determining which view of 2017 wins out.

On Monday, Theresa May heads to Brussels for a meeting with the European Commission. Over lunch, she will set out what Britain is prepared to offer on the financial settlement, EU citizens’ rights and the Irish border. In the days that follow, Juncker will tell the EU member states what has been proposed and a verdict will be reached on whether there has been ‘sufficient progress’ to move on to trade and transition.

If the EU won’t agree to go to the next stage, the British government will walk away from the talks. Or, at least, it wants the EU to think it will. I have been struck in recent days by how those who are normally very careful about the language they use, even in private, have been talking about how insufficient progress this month will mean ‘curtains for the process’. Even those in the cabinet most keen for a deal are quick to point out that it would be very hard to keep negotiating if the EU swallows every British concession, then demands more.

In Whitehall a sense that there will be ‘sufficient progress’ prevails. Government sources say they are close enough on citizens’ rights and the divorce settlement that the Irish border will not derail them. One figure close to the negotiations tells me that they are confident they can come up with a ‘higher form of words’ on the border to give the pugnacious Taoiseach Leo Varadkar ‘a ladder to climb down’. They also believe that the larger member states will lean on Dublin to let the talks move forward.

There is another possibility. The EU could say that the UK has made enough progress to move on to sorting out the transition, but that more is needed on the Irish border before trade talks can begin.

It is easy to make the case for Tory pessimism about the party’s prospects. There are still dozens of ways in which Brexit can go wrong. The cabinet has not discussed, let alone agreed, precisely what kind of relationship with the EU the UK should be seeking. When cabinet ministers press May on this, she likes to tell them that ‘We can’t get into crossing every T and dotting every I.’ But beyond the basics of leaving the single market and the customs union, the UK hasn’t even started sketching out the details of the kind of trade deal it wants.

There remains a distinct possibility that the Brexit talks could break down. But since the referendum result, the UK has made pitifully little progress towards being prepared for a ‘no deal’ scenario. Even if an agreement is reached, there is bound to be some short-term economic uncertainty around Brexit. All of this will make it harder for the Tories to attack Jeremy Corbyn as a threat to economic stability at the next election. The Tories will struggle to pose as the safety-first party, given that they are seeing through the most radical change in the governance of Britain in 40-odd years. So the most obvious attack line on Corbyn — that he is simply too much of a risk — won’t have nearly as much potency as it would in normal times.

Another problem for the Tories is that by the time of the next election, they’ll have been in power for 12 years. After more than a decade in office, voters think everything that is wrong is your fault. The Tories have taken to talking about Labour’s great recession when they try to explain why spending cuts have been necessary. But the truth is that by 2022, few voters will be thinking about Gordon Brown when they go to the polls.

The electoral arithmetic also favours Labour. There are 68 seats they can win with a swing of under 4 per cent, enough not only to put Jeremy Corbyn in Downing Street but also to give him an overall majority.

But there are, for the first time since the general election, reasons for the Tories to think that their glass is half-full. For what it is worth, Labour has not pulled ahead decisively in the polls. This suggests a large section of the public remains resistant to the idea of Corbyn as prime minister.

The Tories can also take cheer from the fact that Britain will be out of the EU by the time of the next election. With Brexit done, legally if not practically, passions should cool, allowing them to woo back those Remain voters who abandoned the party in 2017. It’s hard to believe that the 39 per cent of Financial Times readers who voted Labour in June all wanted John McDonnell as chancellor. The Tories will be helped in this process by having a new leader, who won’t be associated with some of the more divisive rhetoric of the May era. They’ll be better placed to patch things up with the citizens of nowhere and to move the country on from the tensions over Brexit.

This new Tory leader’s aim should be to emulate Harold Macmillan. He became prime minister after Suez, an event that split the country just as bitterly as Brexit has. When he came to office, he was the third Tory prime minister in a row, as May’s successor will be, and the party looked tired after being in government for five-and-a-half years. But he reinvigorated the Tories, bound up the domestic and diplomatic wounds that Suez had caused, and set about showing that ‘life’s better under the Conservatives’. At the general election two years later, the party substantially increased its majority.

If the Tories are to show that life is better under them, then they will have to take another leaf out of Macmillan’s book and build more houses. Intellectually, the government knows that. But until it embraces proper planning reform, it won’t be able to reverse the decline in home ownership.

What the Tories mustn’t forget is that their fate remains largely in their own hands. They still have four years to show voters that life is better under them than it would be under Jeremy Corbyn.

James Forsyth and Fraser Nelson ask whether the Tory cup is half-full or half-empty on The Spectator Podcast.

With Brexit done, passions should cool, allowing the Conservatives to woo back those Remain voters

SPECTATOR.CO.UK/COFFEEHOUSE Hourly updates from Parliament and beyond.