There are two conversations going on in British politics. One is about fiscal policy: getting the deficit down or failing to, modernising public services and boosting the NHS budget. The other starts with immigration and moves swiftly to Rotherham and the abuse of mainly white girls by mainly Pakistani-origin men; and then to Isis, where, according to intelligence, 400-500 UK Muslims are alleged to have joined a terrorist militia.

You may not be directly engaged in the second conversation, or perhaps you find it uncomfortable. But get used to it. Because the implosion of mainstream politics is real.

Many of us are protected from the second conversation. In the media, it is rare to find anybody in a position of power who supports Ukip; newsrooms are recruited from the same broadly liberal elite as the political party leaderships. Likewise, most corporations live the dream of liberal capitalism.

But this is how one Labour politician put it to me: “When I go to the pub in some of our northern heartlands, the debate is now mainly between Ukip and the EDL. We are barely in it.”

That’s not true of all pubs, nor all Labour heartlands, or all the places where Conservatives are losing ground to Ukip. But it is true in enough places to make Ukip’s consistent figures in the opinion polls part of a wider social phenomenon.

Though the second conversation often revolves around the linked issues of immigration, EU membership and Islam, I don’t think it is ultimately about these issues. The deeper issue is identified in special adviser speak as: “People who feel they’ve lost out from globalisation.”

Let’s deconstruct this phrase. Which people? It’s not only white people: those who cheered Nigel Farage in Heywood included black and Asian Britons. Aggregated polling data from YouGov, with a sample of 27,000 adults, shows 42% of Ukip voters polled were Tory voters before, with just 13% coming over from Labour.

In terms of “social grade” – the ABCDE scale – 29% of Ukip voters are from the DE low-income group, but 43% come from the ABC1 group marketers use as a euphemism for the middle classes. So it’s not just low-income people.

But the most striking thing about the Ukip voters polled was their educational background: 76% finished their education between the ages of 15 and 18. No other party comes close to being so heavily concentrated among voters who didn’t go to university. It has nothing to do with “intelligence” – a large percentage of people who vote Ukip simply took a non-academic route to their current place on the income scale.

If you combine this with the fact that Ukip votes spread across all income groups, you come up with the demographic whereby the 2015 election will be won or lost: people who’ve worked their entire adult lives have been shaped by unskilled and semi-skilled hard work.

So what have such people lost from globalisation? Materially, wages. Whether east European migration really does place an extra downward pressure on low-skilled wages is disputed. What you can’t dispute is that those breaking away from the three main parties believe so from experience. On top of that, globalisation – combined with the info-tech revolution – exerts a downward pressure on incomes, “hollowing out” middle income jobs and making it harder to climb out of low pay.

Nobody in power gets to live that experience: there is nobody in parliament, or our major media organisations, or the senior civil service or the boardroom, who has recently delivered homecare in 15-minute slots, or worked in an e-commerce fulfilment centre, or ground out the tachograph hours as a self-employed haulage contractor.

People from this precarious and culturally working class demographic are not the majority of society. But they are one of the few demographic groups whose cultural values and lifestyles are coherent. Critically, Labour, the Liberal Democrats and the Conservatives had each, in their different way, assumed they could always rely on people from this group.

All that’s really happened is that they have, for some reason, simultaneously lost trust with political parties led by people who have only ever been politicians, or special advisers to other politicians. And once you can no longer rely on this group, all the other demographics you need to make a political strategy look fragmented.

What it’s doing to the Conservatives is clear: the centrist project originally framed by David Cameron in the run up to the 2010 election has imploded. The right is being magnetised towards Ukip, while the leadership is moving rightwards in response. Cameron’s flagged intention to call for an end to free movement rights into Britain for EU workers will be the signal moment here.

As for Labour, it soldiers on, determined only to take part in the first conversation – about fiscal policy, public services and a “progressive” project framed around more just forms of globalisation and EU membership. That was the real experience of Heywood and Middleton, where, when people on the doorstep said “immigration”, Labour said “NHS”.

Labour’s strategy is now, in effect, reduced to “staggering over the line” in May 2015, in the hope that Ukip will split the Tory vote in enough seats to give Ed Miliband the largest party. But if that fails, some party insiders believe, Labour too could implode. If Miliband wakes up with anything less than a majority on 8 May – because 13% of traditional Labour voters have voted Ukip – there will essentially be two ways forward.

One is for Labour to become a party of the liberal salariat and the public sector workforce. Another is to become, in party parlance, “blue” – to ditch the policy of free movement of labour and to re-regulate the market in ways that assuage the economic and cultural discontent of the working class. (A third option, where the two wings co-exist, is not seen as likely by Labour watchers.)

Either way, we are beginning to see what discontent with globalisation is doing to the British party system. Any party that does not win outright in May will probably go through an immediate and traumatic change of philosophy – and leadership.

Paul Mason is economics editor of Channel 4 News. Follow him @paulmasonnews