It’s election day 2022 and a mum proudly takes her just-turned-18 offspring to the polling station. Mum: “What’s it feel like to vote in the birthplace of democracy?” Kid: “Great, but do you remember that time when our food ran out, and all the lights went off and the army had to helicopter grandma’s morphine tablets into her back garden…”

The “no-deal” outcome for Brexit is only one possible outcome but it’s a possibility so real that the government has now ditched plans to scare us with the details. The original plan, conceived at Chequers, was to ramp up popular anxiety about no-deal to force the Tory hard Brexiteers into line.

Instead, the Tory Brexiteers have hijacked the Chequers deal, eviscerated it, and are now actively pursuing the project of no-deal, using the very form of words May handed to them over the chintz and petits fours on that fateful Friday.

The full details are concealed. We know they are planning to deploy what’s left of the British army to ferry essential supplies of food fuel and medicine beyond south east England; we know Dover council is contingency planning for parts of the A20 to be made into a permanent lorry park, for five years. As for stockpiling food, it’s not the government’s job, says Dominic Raab: as always, it is “working with the private sector” to make sure we’re not living on cheddar cheese and turnips come spring 2019. But since all civil contingency planning has to assume the worst-case scenario, we should probably be glad we’re not allowed to see it.

If they’re doing their jobs right, those planning for a chaotic meltdown after 29 March 2019 will be factoring in simultaneous cyberattacks from a hostile state that disrupts telecoms and the energy supply; with added dollops of fake news from Boris Johnson’s new best mate, Steve Bannon. Oh, and the possibility that some people react unkindly to the sudden closure of British airspace and the collapse of sterling.

In case you are thinking March 2019 is a long way off, the problem is that the Conservatives have, on my calculations, about six to eight weeks to decisively rule out a no-deal outcome. Parliament returns for a week of backstabbing and intrigue on 4 September. May faces an informal EU heads of government meeting on 20 September (with parliament in recess for the party conference season) and her own party conference in the first week of October. The make or break European Council takes place on 18 October.

Remembering that “nothing is signed until everything is signed”, the already-agreed 21-month transition deal, which puts Britain outside the EU in name only from 29 March next year, could – if the EU27 were feeling ruthless – be in doubt.

At that point, like the commanders of the Imperial German Navy in 1918, facing the end of all their dreams, we should expect a coalition of fascists, xenophobes, golf club bores, Russian stooges and right-wing Tory MPs to launch themselves onto a final no-deal death ride, to the combined soundtrack of Wagner’s Die Walküre and that BNP single “Christmas is a British Thing”.

If the Tories permit a no-deal meltdown, then even if the outcome is a snap election, or a second referendum, or a Poll Tax-style mass revolt, there is no reputational way back for British Conservatism. Just as it is now true for all time that the US Republicans are susceptible to far-right infiltration and manipulation by a foreign power; so it will be seen worldwide that the Conservatives are no longer a party of the multilateral global order.

How did the Tories, renowned for their resilience, adaptability, and intellectual curiosity, end up facing the possibility of destroying the country they professes to love? It used to be said that they thought in terms of “centuries and continents”; now their thoughts are focused on surviving the next 24-hour cycle and avoiding the country’s fragmentation.

We are far enough away from June 2016 now to see it as history rather than news: and all the first hand accounts show that, in the wake of defeat, liberal conservatism simply absconded. Even now, if you look at the Millbank-based coalition centred on Open Britain, leading the fight against Brexit, the most prominent individuals are from liberalism, liberal academia, Blairism, and outside parliament.

Large global corporations, though they lobbied strongly for softer forms of Brexit, mistakenly bought Theresa May’s assurances that everything would be sorted out. Speculative finance, meanwhile, simply adapted itself to new choppiness: any fool can make money out of volatility and Canary Wharf is full of them.

When we look back on the period between the June 2017 election and the day May quits, we will see it as a period in which a gang of chancers and incompetents, with few organic connections to British business and civil society, but with a direct line to US-funded think tanks and foreign crooks, led modern Conservatism to its doom.

Either the Tory party is to be a collective expression of liberal, educated, corporate, global-focused and entrepreneurial interest – or it is to be the parliamentary wing of irrational xenophobia, funded increasingly by foreign oligarchs and intellectually part of Trump’s “nationalist international”. You may think the latter fate impossible, given the centuries-old roots and adaptability of Toryism. But it happened to the GOP in America, it happened to the Austrian ÖVP, and it can happen here.

Because the split in the Conservative Party has material roots. The 27 per cent of the electorate who told a Sky News poll this week they want a no-deal Brexit would probably, if offered, vote for the authoritarian nationalism that comes with it. Meanwhile, an influential part of Britain’s social elite has morphed into a public relations, property management and private security industry for foreign crooks and dictators. Constructing what philosopher Hannah Arendt called the “alliance of elite and mob” around a common programme of authoritarian nationalism would not be hard in conditions of a no-deal Brexit.

What are the realistic alternatives, given the political balance of forces? It’s possible that this week’s flurry of perfidious Albionism, with ministers telling France and Germany to stab the EU Commision in the back, might work. If so, the EU 27 simply accepts the busted Chequers deal, keeps Britain subject to all four freedoms for the next 21 months, and hopes for the best.

Alternatively, the liberal centre of British conservatism reasserts itself: facing down the xenophobic right and regaining control of the agenda. If, however, a Tory leadership challenge decisively tips the party - towards a no-deal Brexit or a Norway-style deal - the government is likely to lose its majority and there’s a snap election.

I’ve covered here before what I think a majority Labour government should do - actively embrace a version of Norway and offer a second vote on the outcome of new negotiations. But what if there’s a minority Labour government? The rumours of “12-20 Labour MPs” preparing to join a revamped Lib Dems, with David Miliband sailing back into British politics on a white swan, continue to swirl. In that situation, the price of SNP supply and confidence would surely be not only a second Scottish referendum plus devo max; it would be a second Brexit referendum and a clear commitment to the single market at the very least.

There’s a theory among the #FBPE (Follow Back, Pro-EU) crowd that the mandate of the original Brexit referendum has a “half life” – ie it decays over time. I prefer a more dramatic metaphor, drawn from screenwriting: the hero's journey.

In a classic Hollywood movie, the protagonist sets out on a journey, hits obstacles, changes tack, hits bigger obstacles, takes even bigger risks and ultimately comes to a crisis point and a moment of realisation, where all his or her assumptions are called into question.

Rather than a steady decay, I believe the pro-Brexit half of the UK electorate will come to a Hollywood style moment of truth: they have set out on the journey, the wrong people were holding the map, now everybody’s lost and time is running out.

In a Hollywood movie, the protagonist returns home with a “boon” or prize: and sometimes it’s not the one they set out to find. A stronger, more socially cohesive Britain, with looser ties to Europe but a clearer orientation towards it, and greater self-knowledge of its own divisions, is a realistic outcome.

I still think achieving Brexit, honouring the mandate, and reuniting the British population around a European-focused politics and economics is achievable; that’s why I want Jeremy Corbyn to embrace the Norway-plus and second referendum strategy. But Corbyn is not in power: the Tories are. Liberal conservatives who have the interests of business and social cohesion at heart, have about six weeks to take control of the agenda.

If the October European Council ends in failure, then the metaphorical troop trains of a no-deal Brexit will start rolling. If you want to understand how bad things could then get, try saying the words “stockpile food” to a working-class mum struggling to feed her kids tonight.