Underneath this country’s worst political crisis in 80 years and the Westminster drama that looks set to reach a crescendo lie deep cultural and attitudinal divisions that will sit at the core of this country for decades to come. For millions of people, a basic stance on Brexit runs much deeper than any affinity they might feel with a political party: recent work by the psephologist John Curtice found that 77% of us identify with either side of the debate to a strong extent, as against only 37% who feel a similar allegiance to a party, with the respective figures for “very strong” put at 44% and a miserable 9%. This is not a country essentially split between Labourites and Tories: we are now either leavers or remainers, with large swathes of each camp motivated by boiling passions.

Obviously, the Brexit divide is only symptomatic of even more fundamental differences. Not long after the referendum, it was no great surprise to read that how voters felt about Europe slotted into their opinions on multiculturalism, social liberalism, the internet, globalisation and immigration; nor that such factors as age, class and education had been central to how people voted. Indeed, when I was out on the road during the campaign, it felt as if an even simpler question would decide the outcome: whether your view of the globalist, liberal future into which the country seemed to be inevitably heading was optimistic, or whether prejudice or a pessimism rooted in deep economic insecurity (or both) had pushed you to the opposite conclusion.

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Now, it would be foolish to pretend that millions of people aren’t contradictory bundles of both sets of views. Moreover, in the sense that pre-Brexit electoral politics often meant that the two main parties had to aim at bringing very different voters together in order to win elections, the gaps between large parts of the electorate were constantly smoothed over. The grim political perfection of Brexit, by contrast, was that it represented a convulsive argument about a package of stuff that went straight to the heart of all of these tensions, and decisively pushed people one way or the other. This was David Cameron’s unforgivable oversight. What had been bubbling away for decades therefore exploded – and, in the manner of a political combustion engine, is now doing so again and again.

Where did it all originate? As with so many aspects of the modern English condition, it is a good idea to start by going back to George Orwell and his brilliant essay The Lion and the Unicorn (1941), partly an exploration of deep English attitudes that still linger. He wrote of an English working class “outstanding in their abhorrence of foreign habits”. But he also took aim at a pious, snobby middle-class mindset that ran deep among prewar progressives, and which one now detects among certain elements of the pro-remain crowd. The words are well-known: “England is perhaps the only great country whose intellectuals are ashamed of their own nationality ... In left-wing circles it is always felt that there is something slightly disgraceful in being an Englishman and that it is a duty to snigger at every English institution.”

Which brings us to the 1960s. It is no accident that many of the politicians – May, Farage, Rees-Mogg – who now sit at the heart of Brexit have the look of people untouched by the huge social changes that originated back then. That decade’s self-expression and social liberalism widened the differences Orwell had described, but at the same time, something else happened. The same rising individualism created the conditions for the laissez-faire economics that first took root in the UK and US in the early 1980s, ravaged no end of industrial communities, and pushed politics away from the kind of collectivist thinking that had started to fade as the shadow of the second world war receded. The key point was made perfectly by the British music writer Charles Shaar Murray: “The line from hippie to yuppie is not nearly as convoluted as some people like to believe.”

By the 1990s, affluence was increasingly synonymous with open, liberal, metropolitan thinking. By contrast, people and places who were left out of that decade’s prosperity felt the urge to reject this idea of modernity, and look for something different. In Britain and elsewhere, it was eventually provided by wealthy right-wingers who had no more experienced economic hardship than they had been to the moon, but such ironies should hardly be surprising: political history is full of them.

With old political models crumbling as the centre empties out, the basic nature of 21st-century debate is becoming clear all over the world. A recent New York Times piece about the success of the German Greens explained that “the party represents a gentrified lifestyle, from healthy eating to a certain self-image, that of liberal nonconformism, that was once considered niche but has become mainstream”, and is devoutly “pro-environment, pro-Europe and pro-immigration”. At the other end of the spectrum sits Alternative für Deutschland, whose front ranks are smattered with former soldiers, and – to quote from Der Spiegel – is seen, particularly in the deprived former East, “as a guarantor against Germany becoming a multicultural society”.

Notwithstanding very German factors, all this reflects not just what is happening in Europe, but the predicament of the US: arguably the first country where a great chasm between liberals and conservatives opened up and the latter eventually embraced reactionary nationalism, with the result that two great demographic blocs now stare across the divide with a mixture of mutual mistrust and bafflement.

Here, we may soon be just as estranged from each other. When I was growing up in the 1970s and 80s in comfortable suburbia, my parents had come from working-class homes into the middle class, but retained the same values that had defined their childhoods, so there was no great cultural gap between me and schoolfriends who came from a wide variety of backgrounds. Cars, houses and holidays offered people some means of keeping up with the Joneses, but there was nothing like the modern consumerist culture built on the constant imperative to somehow appear sophisticated and successful. TV offered three channels. Politics was largely a simple choice between two different views of the state and economic distribution.

But then came the things that have so pushed us apart. Social mobility stalled. Deindustrialisation carried on apace. Insecurity skyrocketed. The complexity of modern society burst into public debate. And our sources of information eventually fragmented, with two key effects. Malign forces found new openings. More generally, we are now close to losing any coherent sense of who “we” are: one of the reasons why all that talk from Brexiteers about the will of the people seems so absurd.

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In the long run, it’s not clear how Labour and the Conservatives will accommodate our modern ferment. At the 2017 election, Jeremy Corbyn’s party piled on votes from young, urban and educated people and the Tories found new openings among working-class Brexit supporters, but the result only highlighted our national deadlock. Though Brexit looks to me like an epochal disaster to which the best answer is probably another public vote, there is another question, which politicians’ inevitable fixation with backstops, borders and customs unions leaves untouched: how the array of deep social and cultural questions tangled up in the events of the last two years will eventually be settled. I also wonder how we construct online spaces, public institutions and media outlets that might protect some coherent idea of the national interest and genuinely public debate. One thing, though, seems obvious: that we are in the midst of things we have only just begun to understand, and the deafening noise from Westminster is only the start.

• John Harris is a Guardian columnist