D J Taylor: The middle classes are in charge. Woe betide anyone who doubts it

The bourgeoisie has become used to having things its own way. Unchallenged, it is prepared to be high-minded, and even radical. But now it is feeling threatened

The Barratt homes of England

How choc-a-bloc they stand

To show the middle classes

Still have the upper hand...

The Crewe and Nantwich by-election offered a relatively unusual spectacle in British politics: the sight of a defending party turning its guns on the wrong target and altogether failing to grasp the way in which the contemporary political system works. Seizing on the background of the Tory candidate, Edward Timpson – a minor public schoolboy and the heir to a chain of boot and shoe repair shops – Labour's strategists somehow convinced themselves that here was an opportunity to persuade working-class voters that the Conservative Party was dominated by "toffs". In doing so, they managed to detach the proceedings from the centralising dynamic of modern political life: the anxieties of the middle classes and their resentment of a government that, in common with every other British government since the days of the 1832 Reform Act, they elected to power.

The part played by middle-class activism – or its alter ego, middle-class quietism – in plotting the trajectory of our national life is insufficiently appreciated. But no politician with the faintest interest in demographic trends can afford to ignore it. Social categorisation, as social historians always point out, is a matter of belief rather than narrow economics; and with the post-1970s rise in home ownership and living standards, the number of people describing themselves as "middle class" in surveys routinely covers 60 to 70 per cent of the population.

This unparalleled recruitment drive has enabled their more affluent members to intervene decisively in dozens of areas of national and regional policy. It is the middle classes, for example, that have largely destroyed the value of state education by choosing to opt out of it. It is the middle classes that sustain the development of our vast, flabby and essentially non-academic university system on the grounds that, in a hotly competitive market, a degree gets you a job. What might be called middle-class sectarianism is one of the dominant features of modern Britain. Its tocsins – house prices, schools, job security, an unwillingness to realise that the rest of the world even exists – clang over every suburb and dormitory town in the south of England, and whichever political party best manages to appease it will win the next general election.

But perhaps, in analysing a category that includes everyone from the Archbishop of Canterbury to Mr Gordon Brown and the "toffs" of the Tory front bench, one ought to start by asking: what does it mean to be "middle class", and what assumptions have attended the middle classes' rise to political power?

Although early Victorian novelists had a great deal of fun with the bourgeois pretensions of the mid-19th century – see the Veneerings in Our Mutual Friend by Charles Dickens or William Makepeace Thackeray's Timmins family which would give its little dinner and is almost bankrupted in consequence in A Little Dinner at Timmins's – one of the first forensic accounts of English middle-class life comes in George and Weedon Grossmith's The Diary of a Nobody (1892). Mr Pooter, its middle-aged clerical hero, is, of course, a figure of fun, but for all the spiritual banana skins that litter his path, he knows exactly what he is, and his belief in his own position is quite as solidly based as, say, his belief in God.

The immense self-confidence that he derives from his job in the City and the domestic comforts of The Laurels, in Holloway, allow him to respect people higher in the social scale than himself (in particular his employer, Mr Perkup, whom he regards as the embodiment of human virtue) while looking down his nose at newer arrivals whose status is founded purely on money.

Then, as now, this insistence on social distinctions is doubly important as it comes at a time when social distinctions are becoming markedly more fluid. In the context of recent English social history, Mr Pooter, with his modest aspirations and his terrific sense of wounded dignity, is a hugely symbolic figure, and yet the historians of the 20th century have sometimes tended to ignore the people he represented. History from the period 1900 to 1950 has a habit of being written from the polar ends of the social scale, either concentrating on the predominantly upper-class cabals who administered its political arrangements or the proletarian hordes seething around its edge. Significantly, the new wave of British social history has turned markedly revisionist.

The message of David Kynaston's monumental Austerity Britain, for example, is that Attlee's post-1945 welfare state, that socialist Jerusalem to whose efficacy all left-wing commentators sentimentally testify, was tolerated for about 18 months until the bourgeoisie lost patience with it. The dominant note of the late 1940s, as Kynaston sees it, was one of protest: middle-class people complaining about anything from new town developments to the refurbishment of bombed-out city centres and turning doubly furious when these representations were ignored by the gentlemen in Whitehall who knew best. Martin Pugh's forthcoming book We Danced All Night takes a similarly iconoclastic line about the inter-war era: a time of great social deprivation and mass unemployment, certainly, but also a period in which the take-up of many of the amenities we associate with middle-class life, from leisure pursuits to foreign travel, increased. If the 1930s had a legacy, along with Jarrow and the rusting shipyards, it was a strengthening of middle-class self-belief: an awareness, common to anyone with more than £500 a year, of who you were and what the world owed you.

Above all, this involved a staking out of territory, a wintry eye for demarcations and protocol. My father, born in 1921, was a perfect example of middle-class self-advancement: proceeding from a council estate via a scholarship to the local public school, to a clerical job that made up in esteem for what it lacked in wages. The result of this ability to "get on" was a profound wariness, both of people higher in the social scale than himself and those lower down: the former might patronise him; the latter might try to usurp him.

Later, as a middle manager irked by the industrial disputes of the Wilson-Callaghan era, he was a keen observer of the crucible in which modern middle-class sectarianism – Mrs Thatcher's great legacy to the modern age – was forged. The dominant emotion of these years was fear – the thought that, in a world of raging inflation, manual labourers had trades unions to bargain for them, while white-collar workers had only deferential staff associations – that the distinctions of the middle-class lifestyle might eventually prove to be symbolic (how you spoke, what you wore) instead of economic.

It is not quite certain when bourgeois unease turned into bourgeois triumphalism, that deeply depressing tribal smugness rooted in real estate, expensive cars and foreign holidays which burns through the contemporary media like a rash. Undoubtedly the mid-1980s' rout of the miners had something to do with it, and so, too, did the break-up of the nationalised industries, loathed by the middle classes on account of monolithic inflexibility, and now ripe to be pillaged via share issues.

Its symbols are everywhere apparent – in the TV channels given over to home improvement and gardening shows, in the habitual affrontedness that stirs whenever anyone suggests that a 4x4 in a suburban street might not be a very good idea – but one of its least attractive features is contempt. The average Victorian bank clerk was scared of the lower classes ("'Ere comes a toff. Let's frighten 'is 'oss," runs the caption to a Punch cartoon of the period); the Attlee-era dividend-drawer might make jokes about miners keeping coal in their baths, but the modern tendency is to outright sneering. Hardly any "educated" person is immune to this, and I will happily own to finding the sight of John Prescott at the despatch box or Jade Goody in interview horribly amusing. I cannot help it. It was the way in which I was brought up.

Even worse, perhaps, is the almost complete extinction of the radical middle-class strain in British life – the strain that animated Clement Attlee and a dozen Labour paladins from Crosland down and whose monuments are strewn all over the political landscape of the past half-century. Practically every enlightened measure of the modern age, when it comes down to it, from the end of capital punishment to the repeal of the homosexuality laws, has its origins in middle-class agitation. There was a brief period, in 1997-98, when Tony Blair appeared to have tapped into this reservoir of high-mindedness and fellow-feeling, only to blow it all on a campaign to appease the Daily Mail.

It is far too late for Mr Brown to do anything about the derelictions and evasions of his predecessor and the discovery that the majority of the bourgeoisie will support you only as long as its status goes unimperilled. The genie of middle-class sectarian resentment was let out of the bottle a long time ago, and we can only stand back and inspect the havoc it looks set to wreak.