Just over 40 years ago, the political scientist Peter Pulzer wrote that ‘class is the basis of British politics; all else is embellishment and detail’, a proposition inflicted on undergraduate politics students as an essay topic ever since. It is no longer as obviously true, but it certainly still has more than a grain of truth in it. So how important are Labour’s traditional core vote? Of course they matter, but are they crucial to electoral success or survival?

There are still in the region of 200 seats with a white working-class majority, most held by the Labour party. Those where the dominance is strongest include many in Scotland and South Wales, as well as the English inner-city seats in the north – Hull East, Stoke North, Barnsley East and several of the Merseyside constituencies, for example. But these seats are mostly so safe that the political leverage of even so large a group is limited unless they are capable of acting en bloc.

What does this mean in voting terms? What is key is that people’s own perception of their class is related strongly to their political opinions, more closely than their objective social grade. David Butler and Donald Stokes found the same in their seminal report of the first British Election Survey: people with ‘middle class occupations’ who regarded themselves as working class were much more likely to vote Labour than those who did not, while the reverse was the case with voters in ‘working class occupations’ who regarded themselves as middle class.

A modern Labour government needs some middle-class support to survive, and that is obviously true if one thinks in terms of the rise of the ABC1s to comprise half the population. But it does rather assume that these ‘new’ middle classes think and act as middle classes. We also need to consider the working classes and how they think and feel – the fact is that working class people who ‘feel’ middle class are more than twice as likely to support the Tories as those who feel working class. This tendency of the ‘aspirational’ working class to vote Tory was of course one of the factors to which the successes of Margaret Thatcher in the 1970s and 1980s was attributed. This was combined with policies that fostered this phenomenon such as the sale of council houses to their tenants.

But as the working classes have shrunk in number, there are not very many ‘middle class’ C2DEs (the traditional classification of members of the working class), and a lot of ‘working class’ ABC1s – in fact, half of all C1s feel working class rather than middle class. The development of this position is, of course, an important reason why the class element in British voting seems to have weakened over the years. What has really weakened is the relationship between respondents’ self-assessed social class and their class as objectively.

This has crucial implications for election strategy. If the class factor that affects voting is an objective economic phenomenon, beyond the scope of short-term electoral campaigning, then come the election the parties would just have to make the best of it; but if, as seems to be the case, the relevant factor is primarily a subjective one, then like all other perceptions feeding into a voter’s electoral choice, it can be manipulated by party campaigners. Voters’ self-image, as much as the image of the parties, matters. Labour benefits when more people think of themselves as ‘working class’ and therefore should find a way to play up to this and encourage them to do so. Whether ‘toff-baiting’ is the way of doing it is another matter.

Nationally, class still matters more than race, given the relative size and concentration of BME communities. There are significant numbers of white working-class voters everywhere, even in the most middle class or ethnic-minority-dominated areas, and that implies that they would hold the balance of power in any number of marginal seats were they to use it collectively, and vote on class interests.

And here lies the issue. Profound changes in class voting patterns have been seen in the past few general elections. When Harold Wilson narrowly won his last election in October 1974, Labour took 40 per cent of the total vote, but just 19 per cent of the ‘middle class’ (ABC1) vote, meaning that only an eighth of his support came from outside the ‘working class’; by contrast, in 2005 Blair’s middle-class support was 30 per cent, which, because turnout is higher among the middle class than the working class, made up nearly half of the whole Labour vote. Labour not only successfully appealed to the demographic middle ground but made significant inroads into the Conservatives’ ‘natural constituency’ – a necessary development for the party of the left in a country where the middle class has expanded from barely a third of the electorate in Wilson’s day to more than half now.

Indeed, it would not be too much to say that appealing to the middle classes has saved the Labour party from the near certainty of electoral extinction – given current patterns of differential turnout, a party relying solely, or even mainly, on working-class votes would inevitably lose. This altered pattern of class voting is one that future Labour leaders should be very wary of jeopardising.

Labour has won by appealing beyond a shrinking group in society. In fact, in 2008 only 39 per cent of the public think the Labour party is the party that best represents working-class people and 10 per cent think the Conservative party does. More to the point, 21 per cent say no party does, and a further 17 per cent don’t know. Worse, ABC1s (41 per cent) and those who considered themselves ‘middle class’ are marginally more likely (41 per cent) to think that Labour is the party representing working class rights than are working-class people themselves (36 per cent), and this was before the 10p tax debate.

But of course, many of the public hold opinions about their class which defy conventional research classifications. When we asked the public to classify themselves as middle class or working class, 57 per cent of them said they were working class and only 40 per cent middle class. Indeed, back in 2002 we found that 68 per cent of the public agreed with the statement ‘at the end of the day, I’m working class and proud of it’, as indeed did 55 per cent of those who we would normally in our surveys call ‘middle class’, the ABC1s.