The dominance of the global market, in labour as well as capital, allied to prevailing ideologies about the acceptable limits of state intervention, has left Chancellors of the Exchequer more constrained than they have been for several generations.

When he came to office in May, Gordon Brown had already committed himself to maintaining Tory public spending targets and taxation levels. Within days, he had handed over control of interest rates to the Governor of the Bank of England. He had thus, to all intents and purposes, relinquished control of the two levers that Chancellors customarily use to steer the economy. Sometimes, I wonder what Mr Brown now finds to do all day.

In the 1950s, ministers acknowledged that the school curriculum was a secret garden, tended by teachers. The government was expected to keep out of it. Now, the economy is a secret garden, and the gardeners are bankers and employers, while politicians offer no more than occasional advice about the appropriate manure and exhortations that the more tender plants should be treated gently. The teachers’ garden, meanwhile, has been not so much taken over as trampled underfoot by herds of rogue elephants.

So, if education becomes the main instrument of domestic policy, what in practice does this mean? Can the education system be used, for example, as a means of achieving greater social equality? I know that equality doesn’t, at the moment, look as if it is a very high priority for New Labour. But then perhaps, in 1979, inequality didn’t seem all that high a priority for a government led by a woman who had quoted St Francis of Assisi on the doorstep of Number 10. Nevertheless, slightly deranged people were hard at work in places like the Adam Smith Institute and the Institute of Economic Affairs, with such ideas as privatising schools, issuing vouchers to parents and publishing league tables. They didn’t achieve all their aims, but they did succeed in altering the agenda. Their mission was to think the unthinkable; the Left needs to do something similar if it is ever to regain momentum.

The extent to which the Left held the intellectual initiative in the 1970s is sometimes forgotten. We had Ivan Illich and others proposing various forms of de-schooling. We had William Labov arguing that the street-talk of American blacks was just as valid a vehicle for critical discourse as standard English.

In the mid-1970s, I wrote an article for the New Statesman proposing that it should be unlawful for employers to advertise jobs and select applicants in terms of general educational qualifications, such as five O-levels, two A-levels or a second-class honours degree. The uncertificated, I argued, should be as entitled to protection, on grounds of civil rights and equal opportunities, as the ethnic minorities or the disabled; employers should demand certificates only when they represented skills or knowledge that were directly relevant to the job. This was not then an outlandish view. Similar proposals had been made, in all seriousness, by official commissions in Canada and Australia.

Some of those ideas were simply foolish; others were too far ahead of their time (when you learn that the number of US children educated at home has jumped from 15,000 to 350,000 in a decade, it looks as if Illich et al may fall into that category); others pushed too much at the boundaries of public acceptability. The Left, indeed, was almost too fertile with ideas and laid itself open to charges of looniness. Something similar has happened to the Right in the 1990s.

The Left should be ready to think freely and bravely once more. Suppose that we want to achieve greater equality through the education system, rather as Left governments once aspired to achieve it through the tax and benefit system? What unthinkable thoughts would help us?

I start from the case made by Andrew Adonis, joint author of a recent book on the British class system, in an article in last week’s Times Higher Education Supplement. In Britain, he wrote, a system of virtual educational apartheid exists. Private schools and the 161 remaining state grammar schools, most of them in affluent areas with a largely professional client le, are the motorway system of modern British society.

Educating barely 9 per cent of children, they dominate the entry not just to Oxbridge but to all Britain’s traditional universities and thereby to all its elite professions and institutions. They are at the heart of the Super Class - a new upper class of mostly private-sector professionals, concentrated in London and the home counties, at once meritocratic yet exclusive . . . and increasingly divorced from the rest of society by wealth, education, values and lifestyles.

Now we can’t abolish private education because that would probably fall foul of European human rights conventions and, in any case, the schools would just move abroad. So what to do? Simple. We introduce quotas for university entry. They don’t need to be exactly proportionate: if we reserve, say, at least 88 per cent of the places in each university for pupils from state schools and colleges, the educational ball game would be changed overnight. (At present, the private sector gets about 25 per cent of the places, but considerably more in the top universities.) The incentive to pay for private education would be enormously reduced. Many professional parents might calculate that their children’s chances of university entry were actually greater in the state sector. Britain’s educational apartheid would be at an end. Comprehensive schools would at last be genuinely comprehensive, with a balance of abilities and backgrounds. Children at all levels would benefit.

Unthinkable? Well, America has had, if not exactly quotas, affirmative action on behalf of its black minority for a generation. The policy has been widely resented and is now starting to fade away. It is certainly not an unqualified success. But it can hardly be denied that it has helped to create a black middle-class where none previously existed. America in the 1970s thought that its race divide was important and damaging enough to justify such a drastic departure from normal standards of fairness and equity. Isn’t Britain’s class divide just as damaging and isn’t there a similar case for drastic action to end it?