Never over-interpret your own experience when pontificating on education policy, that’s the rule, apparently. We are more prone to do it the older we get of course. As we enter our anecdotage it is easy to forget that school was thirty years ago or more ago. A lot has changed, surely?

In my case, having attended a large comprehensive school in the West of Scotland (from the age of 14, hence the lack of a Scottish accent) the requirement to exclude personal experience is mitigated by nothing – nothing – having been done in terms of Scottish education reform since then. Quite remarkably, despite the evidence of the appalling attainment records of many large Scottish state schools, the political class there and the teaching unions persist with the myth of Scottish exceptionalism and the lie that the education system is brilliant. So a big, middling comprehensive is not that far on from where it was in 1986. Anyway, the experiences of those of us who went to such schools are as valid as the views of anyone else, and usually more valid than the views of people who went to elite schools but who now lecture the rest of us about what works and what does not.

Indeed, as we get into another row about grammar schools, following Theresa May’s announcement that the government will approve some new grammar schools, my blood starts to boil. People who went to Eton, or to openly selective public schools, share/tweet studies about the poor record of selection in producing social mobility. Their followers nod and reply with knowing little asides, about the perils – the horrors! – of grammar schools and the percentages of pupils with free school meals and all that. They base their denunciations on the small number of remaining grammar schools, which are clusters in Kent and Buckinghamshire for affluent parents who can afford to live nearby.

Attending a middling to failing comprehensive school does tend to give you a different perspective on these matters. These are places in which half the pupils are bouncing off the walls in frustration when they should be doing something more useful than being trapped in the bottom stream for languages. The hardworking, bright or just non-violent need to keep their heads down to avoid the attention of the hardcases and their accomplices (who are often perfectly fine individually but who had to choose a side and chose the nutters). This goes on for the first four years or so, alleviated by streaming, but not eliminated because a school is as much about what happens in the school corridor and at the gate as it is about the classroom. Then comes the change, when the disruptive start to leave and the non-disruptive emerge, blinking in the sunlight tentatively at first wanting to be sure the hardcases are gone and it is ok to have a normal conversation. The atmosphere changes. By the 5th and 6th form it is a different school. Academic achievement is not a matter of shame.

Another problem with that model. My school was enormous and difficult for teachers to control. Having been built in the 1970s, when such things were deemed old-fashioned, there was no hall in the school big enough to take the whole school or hold a whole school assembly. As a result there was little sense of ethos or community across the age groups.

It was a typical West of Scotland comprehensive, and the waste of human potential involved is mind-boggling. Whole generations have passed through this system and been let down, but what is interesting is who suffers. Like many middle class pupils I was fine, of course. The affluent middle classes usually are, and going to a toughish school is a good experience if you come through the experience well. At home there was always that added support and spur to learning, whether that meant being taken to the theatre or encouraged to read newspapers and books. And there were some brilliant teachers at school who went above and beyond the call of duty.

The waste comes in three large categories. First there are the non-academic but bright, sparky, resourceful kids who are stuck in a rigid system when at 13 or 14 they should be offered something much more useful in terms of making a career in industry, commerce and public services. The English University Technical Colleges – which are new and need more development – are an attempt to provide such an outlet in science, engineering, industry and computing. Crucially, their originator, Lord Baker, believes quite rightly that the 11+ is a disaster. It is at the wrong age. The ideal switch to different types of schools which match talents to schools is 13, the age (funny that) that the elite private schools already use. It’s almost as though the rich have a secret they are keeping to themselves…

The second wasted category is potentially academically bright poor children, who should be given a shot at an elite education (free of the predations of violent and disruptive peers) which gives them a chance of becoming the professionals, lawyers, bankers, managers, mandarins of the future.

The third category are the accomplices of the disruptive and the disruptive themselves, who are let down by not being equipped with the basic building blocks of a productive existence: structure, order, empathy, reading and writing.

In England, there has been much change that is positive already. After a generation of reform by the Blairites and Michael Gove, the Academy programme and free schools have disrupted the old complacency and set England on the road to improvement. But more needs to be done.

The answer is not – repeat not – a wholesale reintroduction of grammar schools at 11 and secondary moderns. Something much more imaginative is required. Let a thousand flowers bloom, as they say. Surely – with a little imagination and experimentation – we can construct a system that fosters sufficient schools matching the contrasting needs of pupils? Put elite liberal arts schools into some of the poorest areas, and draft in teachers from successful state schools and public schools to help; create coding camps and more round the year maths and English initiatives in poor areas that adults who failed at school can use too; try new models of schools, alongside the Academies and UTCs. Corral the wealthy to help pay for a national drive to improve education in a new burst of US-style giving. The point is: we should avoid getting stuck with old thinking when the world and technology are changing fast.