During a speech on welfare a few months ago, Ed Miliband repeatedly referred to Labour as the "party of work". "The clue is in the name", Miliband told the cameras, hoping, presumably, that voters would see Labour as the champions of working people, rather than idle ones.

The idea that Labour remains the party of the proletariat is partly the basis of Miliband’s so-called '35 per cent' strategy - the idea that a coalition of Labour’s core voters and disaffected Liberal Democrats can sweep Miliband to power in 2015 with just over a third of the vote (with no need to servilely seek the support of 'middle England'). Swathes of blue-collar working class voters, mainly in the north of England, will turn out to vote Labour in any election come what may, so the logic goes. It is the Labour Party, after all, and the "clue is in the name" - it is the party of labour, the working classes.

The problem is that increasingly it isn’t. Or at least it isn’t representative of working class opinion in the sense it once was. On many economic questions the left may represent the interests of the working class more effectively than the right, but, socially, the values of the traditional working class are increasingly at odds with those of the liberal or 'progressive' left.

The main divisions one finds are over immigration and welfare. The middle classes tend to associate immigration to the UK with things like fancy restaurants, new music and a Polish cleaning lady who makes a better (not to mention cheaper) fist of cleaning the office than her British counterpart. For the working classes, however, migration is all too often interpreted as meaning stiffer competition for wages and the loss of the sense of community in the places where one grew up. As the authors of the 2012 British Social Attitudes survey put it: "[In recent years] economically comfortable and culturally more cosmopolitan groups show little change in their assessments of economic impacts [of immigration], but economically and socially insecure groups have become dramatically more hostile."

Differences in perception are also stark when it comes to welfare. The metropolitan left readily accuse Miliband of betrayal if he so much as hints that he won’t reverse coalition policies on social security once in office, yet Labour’s core voters are the most enthusiastic proponents of welfare reform - almost half believe that if benefits are cut it will help people stand on their own two feet. Attacking the coalition for embarking on welfare reform (as opposed to criticising the way reform has been carried out) is ironically more likely to repel working class voters than persuade them to vote Labour.

A similar chasm between working class voters and the middle class left is already well established in the US, with the result that the Democrats are today viewed predominantly as the party of wealthy white liberals and ethnic minorities. What we might call the traditional working class - whites without college degrees - backed John McCain by 58 per cent to 40 per cent in the 2008 election and George W Bush in 2004 and 2000 by a similar margin. In 2012, middle-class white voters who said they were struggling to maintain their financial position chose Mitt Romney by 58 per cent to Barack Obama’s 32 per cent.

Back in Britain, the chasm in attitudes between the middle class left and the more socially conservative working class has always existed but has been exacerbated in recent times by the popularisation of identity politics – white working class men, however much they are struggling financially, absurdly register as 'privileged' on the identity politics totem due to their whiteness and what is between their legs. Meanwhile, positive discrimination and quotas provide a much needed (and justifiable) leg-up for most disadvantaged groups in society, yet by excluding any recognition of class from the process, the same policies leave the white working class falling even further behind – despite the fact that class remains a much greater determinate of a person’s life chances than skin colour or gender.

This is not to say the left should crudely pander to ultra-regressive views on migration and welfare. But nor should it completely ignore the concerns of its so-called core vote. Unfortunately, thanks to identity politics, many progressives appear willing to dismiss the white working class as socially backwards and not worth listening to (notice how those attending English Defence League rallies get almost as much abuse heaped on them for their football shirts and beer bellies as for their racism).

Unless the left is comfortable becoming a movement of upper middle class liberals and ethnic minorities (no shame in that of course), it ought to start listening a bit more to the concerns of its electoral base while it still has one. For, to paraphrase Bertolt Brecht, it isn’t possible to dismiss the working class and elect another.