The other day, I was reading a newly-published volume of lectures by the great left-wing historian and anti-nuclear campaigner E P Thompson. My first thought was that Thompson, who died in 1993, was a desperately sad loss for the British Left: nobody writing today comes anywhere near matching the sweep of his historical vision, the passion of his prose, the sheer vitality of his intellect. Had I been approached by Waterstone’s, I would have nominated only one work for the Books of the Century exercise: Thompson’s The Making of the English Working Class.

But these particular lectures prompted other thoughts - and they concern the way we prepare our young people for life and how much that has changed in the past half-century. The lectures, given at Stanford University, California, in 1981, told the story of EP’s elder brother, Frank Thompson. Frank joined the armed forces at the outbreak of war in 1939. By 1944, he was leading a secret mission in Bulgaria in support of local partisans. He was captured and executed by firing squad. He was 23.

What set me thinking was a throwaway line in E P Thompson’s account. He had found it difficult, reading his brother’s letters and tracing his experiences, to remember that he was so young. But, Thompson said, that was in the character of the times: the resistance movement in Europe was a movement of the young. “Now we spin out the business of coming to maturity much longer, sometimes far too long.”

In one sense, that is not quite right. Men of Frank Thompson’s background - he was a Wykehamist - made a seamless progress through boys-only prep and public schools to boys-only Oxbridge colleges and then to what, in those days, were almost certainly boys-only professions in, say, the City, the armed forces, the law or the Church. You could argue that this was an extraordinarily sheltered and monastic upbringing, that they never had to reach any kind of maturity and that only the special circumstances of war forced adulthood upon them. And you could further argue that even a great left-wing historian was capable of being a bit of an upper-class chump if he couldn’t see all that.

Yet EP’s comment prompts two further thoughts. First, for large sections of the population, we have almost doubled the period of full-time education. My parents belonged to a generation which commonly left school at 14; my children belong to a generation which, given the growing need for further qualifications on top of a degree, often continues studying until its mid-twenties. Indeed, combined with other social trends (long working hours, late child-bearing, early retirement), this suggests we are approaching a new pattern of life: one-third preparing for work, one-third working round the clock (not just at the office, classroom or whatever, but also caring for children), one-third recovering from work.

The second thought is that, when Frank Thompson was a young man, there was no television, no videos, no computer games, no Ecstasy, no pop culture. Youth was an invention of the 1960s. Despite their sheltered upbringing, Thompson and his peers were forced, at least in the cultural sense, to become adults because there was no other culture available to them. He was clearly an exceptional young man and his circle (many of his letters were written to Iris Murdoch) included other exceptional people. But there was a seriousness in their approach to politics, history, philosophy and literature - to say nothing of a breadth of reading and a willingness to throw themselves into foreign languages and cultures - that is almost inconceivable among even the best of my generation, let alone younger ones. And I do not believe - remember the Workers’ Educational Association classes, the libraries in miners’ institutes, the vigour of the trade union movement - that this seriousness was confined to an upper-class elite.

The late 20th century has seen the growth of two enormous industries: education and entertainment. I fear that the one, which set out with such admirable aspirations, has done little more than create a captive market for the other - for the shallow, brittle, glossy and essentially frivolous culture of pop and advertising. Thompson’s generation and class, peace permitting, may have stayed in full-time education until they were 21. But at least they knew why: they were being prepared as an elite to run a country and an Empire, and they were well aware of that role from a very early age. Our modern students have no such clarity. Some may indeed enter the elite professions, but they are just as likely to be forced into the kind of routine jobs which, a generation ago, would have been filled by 16-year-old school-leavers. As the joke has it: “How do you address an Oxford first-class honours graduate?” “A Big Mac and fries, please.” We deny our young people any true role in society until well into their twenties. We do not take them seriously, so why should they be serious?

That is why I am glad that the Government, in its evidence to the Dearing inquiry, has raised questions about why we are expanding higher education and whether we should continue doing so indefinitely. In a remarkably short space of time - under a decade - we have moved to something like mass higher education. We have given very little thought to what we want from our new generation of graduates and to the aims of what has become, socially if not physically, a prolonged adolescence.

We rack our brains for ways of financing universities but never ask if, in their present form, we ought to be financing them at all. The idea of lifelong education is still bolted on to a system that is designed mainly to educate the young. What if we were to turn it on its head and regard a degree taken before starting work as the exception rather than the rule - an exception that would be suitable for only a handful of people (doctors and dentists, say) who need large quantities of specialist knowledge before they are let loose on the public? And what if we were to devote our resources instead to spreading education, both general and vocational, throughout people’s lives? Can anyone deny that we would have a better-educated population, healthier and more fulfilling working lives, and greater maturity among the young?

I fear that these questions are too large for any government we are likely to get. I like to think that they would not have been too large for either E P Thompson or his brother.