I'm usually sceptical about the compartmentalisation of people into separate political 'tribes'. I suspect that people move between them more easily than is typically assumed. Last week pundits were making some fairly gloomy forecasts as to the future of the Labour Party based on a new study which found that 77% of voters now see themselves as centrist or right of centre.

But much of the resulting analysis seemed to get things the wrong way around: fewer people probably identify as on the left because fewer people wish to be associated with an unpopular Labour leader and a party which looks as if it is in turmoil.

Put another way, if a political leader they like (or at least like a little better than their opposite number) is seen as on the centre-right, it seems a fairly safe bet that a significant proportion of the public will feel like they ought to be on the centre-right as well. Only masochists want to be associated with a loser, after all.

It isn't a left-right thing. It's more that, as Professor John Curtice put it last year, Labour looks 'incapable of providing the skills and leadership needed to take the country anywhere at all'.

This point was demonstrated by another recent study which found that, on economic questions at least, the British people lean to the left. What sort of centre-right 'consensus' is it, then, that supports nationalising the railways, increasing taxes on the rich and taking away charitable status from private schools? Once you decouple political questions from their respective parties, things get complicated.

Corbyn, Smith
Jeremy Corbyn, Owen SmithReuters, Getty Images

If political tribes matter, it is the two political tribes within the Labour Party that ought to be of greater interest at the present time, for they look increasingly irreconcilable to one another. On one side is the traditionally left-leaning demographic that does well out of globalisation, and on the other is the demographic that at least perceives itself as losing out.

The main fault line between the two at the present time is immigration. Labour's liberal tribe view immigration as cultural vibrancy and economic growth, while its working class tribe experience increased competition for work and cultural dislocation ("There's literally no one to talk to at work anymore", was how one employee for B&M Bargains recently put it to me).

Labour's first tribe is far more likely these days to get angry about an article from a Labour MP bemoaning the effect immigration has on the pay of its second tribe than it is about the phenomenon itself.

This is fairly well-covered ground. But what's interesting is the commentariat assumption that the two tribes can somehow be reconciled; that Labour is invariably a permanent fixture of British political life.

Former Labour leader Neil Kinnock made this point unintentionally when he said over the weekend that if Jeremy Corbyn won the current Labour leadership contest (which looks increasingly likely) there might not be another Labour government in 75-year-old Lord Kinnock's lifetime. Beyond the gloom-ridden prophesy is the unspoken assumption that there will, at some point anyway, be another Labour government – perhaps just not for a couple of decades.

But what if, as far as the Labour Party's electability goes, it is all over – but over in the sense that the final whistle has been blown and half the team is already making its way down the players' tunnel?

As should be obvious by now, this goes way beyond Jeremy Corbyn's leadership. If you look at the direction politics is moving in developed political economies, social democracy is in crisis.

In Britain in 1951, the Labour vote was close to 14,000,000, and Labour's share of the poll was 48.8%; in 1979, the corresponding figures were 11,510,000 and 36.9%. By 2015 Labour's vote was 9,347,304 and 30.4%.

The Liberal Democrats may currently be in the political doldrums, but with the decline of the working class as a mass political force the situation is propitious for a return to the Liberal versus Tory politics which characterised British political life until fairly recently.

It is inevitably harder to be the party of labour when the industrial working class is nowhere near the force it once was.

As Labour MP Jon Cruddas pointed out at the George Lansbury Memorial Lecture in 2013: "The mass political party of the twentieth century that George Lansbury led is gone. The cultures and social formations of the industrial working class that gave it life and sustained it have gone."

New Labour was a compromise between Labour's liberal metropolitan wing and its traditional working class 'core vote'. During a long period of economic growth this coalition just about held firm. But you cannot redistribute wealth if there isn't the growth to redistribute.

The good times are over, and there is a fundamental uncertainly about what the Labour Party is for in the twenty-first century that hinges around one very big question: is it unapologetically in favour of globalisation or does it want to take the lid off with a little more caution?

If Labour is to win power again, its liberal faction will, whether it likes it or not, have to reach some sort of compromise with working class supporters over issues like immigration. There can be no 'progressive majority' without it.

Labour is already haemorrhaging these voters to Ukip - Labour support from unemployed and non-skilled voters declined from 48% in 2005 to 30% in 2015. Yet the difficulty will lie in compromising without making the same assumption of liberal Labourites as was made about working class Labour supporters during the New Labour era: that they have nowhere else to go.

The Liberal Democrats may currently be in the political doldrums, but with the decline of the working class as a mass political force the situation is propitious for a return to the Liberal versus Tory politics which characterised British political life until fairly recently.

Labour must walk a political tightrope, then, and there is little to suggest that either Jeremy Corbyn or Owen Smith have grasped the scale of the task. George Dangerfield once famously wrote a book entitled the Strange Death of Liberal England. It is not inconceivable that the politics of the twentieth century will look to future historians like a blip. And if the party of Keir Hardie is unable to straddle the middle ground between its two twenty-first century tribes, we may soon be reading similar tomes about Labour's demise.