A number of political commentators have been making the point in recent days that the election was supposed to be about Brexit but has turned out to be about care for the elderly and trust in Theresa May.

I get it. Confusion over the extent of pensioners’ financial liability for their healthcare when things go seriously wrong set alarm bells ringing across an important section of the electorate. Senior citizens and those in their late fifties and early sixties were already concerned about the ending of the triple lock on pensions. To be told that they might have to sell their family homes to ensure they get the care they need in the event of severe mental or physical trauma was just about the last thing they needed to hear two weeks from polling day.

But here’s the thing: the election really is about Brexit. Nothing more important is going to happen to our country over the course of the next parliament than our departure from the European Union. Of course, old people must be looked after. Of course, the NHS must be strengthened. And, of course, something has to be done to end the scourge of Islamist terrorism. But the fact that Britain is about to turn its back on a vital relationship with its European neighbours that has endured for the last 44 years is fundamental to our economic prospects and our sense of who we are. If we don’t get it right, we will suffer the consequences for decades to come.

What appalls me in the face of this incontrovertible truth is the fact that neither Theresa May nor Jeremy Corbyn appears to understand that Britain has become dangerously isolated. Mrs May seems to think that with a large majority at Westminster (and we’ll see how that works out), she will be able somehow to impose a settlement on Europe, or else walk away with her head held high. The Labour leader, by contrast, appears to have little interest in the subject. As far as he is concerned, the EU is a workers’ rights body and little else. He just doesn’t care.

Both are ignorant. But given that the Tories will form the next Government, not Labour, it is the May doctrine that raises the bigger question.

Contrary to what we read in the newspapers, the “divorce” settlement is the least of our problems. The bill we will finally be asked to pay will be large, but not astronomic. Remember, the proposed new Hinkley Point nuclear power station will cost at least £25bn. The total cost of replacing Trident could, according to one estimate, exceed £200bn. HS2, the high-speed rail link from London to the north of England, is projected to cost £56bn, though it will almost certainly exceed that amount by at least another ten billion.

Only if both sides dig in their heels will the UK/EU divorce bill prove the catalyst for a much larger tragedy. What is really at stake in the negotiations due to start next month is Britain’s relationship with by far our most important overseas market accounting for some 45 per cent of our total trade. The Prime Minister’s obdurate refusal to even countenance remaining in the Single Market and the Customs Union has been accompanied by the assertion that we can somehow negotiate full and frictionless access to the European market, allowing British exporters all the advantages of tariff-free trade with none of the costs. In the same vein, while denying EU citizens the right to come to live and work in the UK, the Government imagines that that we can lean on Brussels to issue the City of London with the right to trade feely in the Eurozone.

This is madness. It’s not going to happen. Some may still tell themselves that no deal is better than a bad deal. But with Theresa May at the helm, no deal may in fact be all that is on offer.

Over the weekend, Germany’s Angela Merkel made it abundantly clear that she is ready to move on not just from Europe’s relationship with Donald Trump’s America, but from Theresa May’s Brexit Britain. Emmanuel Macron of France takes the same view. For both these leaders, a new Franco-German alliance is at hand that, with Britain out of the way, will remake the EU, restoring not just its economy but its place in the geopolitical hierarchy.

The truth is that we have already been written out of the script. The EU has left us standing. It has far more important things to do than obsess over Britain’s amour propre and is unimpressed by Mrs May’s bluster. Yes, they will try to screw as much money out of us as we take our leave, and, yes, the old East Bloc will bleat about the rights of its citizens living in the UK. But the idea that Germany thinks its car exports to the UK are more important than EU cohesion, or that Italy will base its approach to Brexit on sales of prosecco, or, most bizarrely, that other members states will be queuing up to follow Britain’s example amounts to nothing more than idle fancy.

Doubters should recall that no far-right leader has been elected in Europe this year. Instead, moderation and good sense have reasserted themselves. Single Currency doomsayers might also have noticed that the euro is well on the way to recovery (with important reforms to come) and that the economies of France, Spain and Italy are all on the turn. No one pretends that there won’t be problems along the way. How could it be otherwise? But it’s not as if Britain, even before Brexit, hasn’t had to face up to its share of these – not least terrorism and the collapse of sterling.

I do not possess a crystal ball and I can’t tell you what Britain will be like in another 44 (or 46) years’ time. But I can say with confidence that unless we tread extremely carefully over the next 18 months we will be less than we were and likely to remain so. If we are serious about maintaining vital ties with our European neighbours and continuing to share in their prosperity, it is absolutely vital that we go into the Brexit talks with an open mind. Mrs May needs to wise up. From Great Britain to Little Britain is but a step.