Martin Parsons is an author and writer on current affairs and international relations.

There is a myth that is being propagated by opponents of grammar schools that “grammar schools are great for the children who go to them, but terrible for those who don’t”. This claim, largely made on the basis of “evidence” from schools in the 1960s and 70s, needs to be challenged.

I began my teaching career in a secondary modern school in Southend-on-Sea. It was a challenging school to teach in: my head of department told me that if I was still standing up after a lesson with the fifth form (now Year 10), it should be counted as “a success” – she had been pushed out of the way by a skinhead when she started and ended up with a broken shoulder.

Many students came from fairly dysfunctional families, the majority of which also had pretty negative attitudes towards education – and ordinary teachers like me weren’t allowed to meet parents in case we got hit. Yet the biggest problem was the euphemistically-called “progressive” approach to education pursued by some local primary schools. It left many children starting secondary school quite literally unable to read. We had two brilliant special needs teachers who used to pull them out of normal lessons and teach them to read within half a term. I vividly recall being left with a first year (year 7) Geography class with only seven or eight students, since two thirds of the class had been withdrawn so that they could be taught to read.

My point is that were and continue to be a whole variety of factors that affect school success, the largest of which by far is the attitude of the family to education. There is a serious danger of looking back to the 1970s and saying: “these schools didn’t always do too well, and the cause was obviously because they were secondary moderns”. In fact, although school education has improved enormously since I started teaching, many similar problems exist in struggling comprehensives: children from dysfunctional homes and even normal homes, in which education is simply not valued and where there is little or no aspiration.

Not only is the myth that grammar schools are bad for those who don’t get in largely based on questionable and often anecdotal evidence of what happened in the 1960s and 70s, but it ignores what is happening today. Many secondary modern schools are judged good or even outstanding by Ofsted. Statistics produced by the Commons Library in June show that, in 2014/15, of the 501,242 students in comprehensive schools, 56.7 per cent achieved five or more A*-C grade GCSEs including English and Maths; of the 22,493 students in grammar schools 96.7 per cent achieved this.

Meanwhile, among the 19,329 students in secondary moderns 49.7 per cent achieved this standard. In other words, the percentage of students in secondary moderns achieving this level was only seven per cent less than the comprehensive school average, even though typically grammar schools take around 25 per cent of the most able students. Now if you add together the actual number of grammar school (21,750) and secondary modern students (9,606) achieving this leve, it shows that, together, 75 per cent of these students achieved 5 A*-C grades including Maths and English – which is 18.3 per cent higher than for comprehensives. In other words, the statistics actually suggest that, nationally, students of a similar ability do better not just in grammar schools than comprehensives, but also in secondary modern schools than in comprehensives.

As John Glen has observed on this site, underlying the argument against grammar and secondary modern schools is an argument about mixed ability classes. It is sometimes true that these can create aspirations for the less able. However, students are generally likely to do best if taught close to their actual ability level. That is the strength of secondary moderns. Moreover, whilst highly motivated bright students can achieve in mixed ability classes, less well motivated able students, particularly those from families with low educational aspirations, tend to underachieve. These are the people the comprehensive system lets down.

I saw this at first hand helping set up a new sixth form college in a coastal town in which virtually all our students came from failing comprehensive schools. Within two years, we had massively improved A-level results in the town and the numbers going to university. There were one or two bright students who, despite all the odds, had managed to achieve a string of A*/A GCSEs in failing schools by working hard at home. But there were a much greater number of bright students who had seriously underachieved in local comprehensives. However, when placed in an A level class alongside other students of similar ability and pushed to achieve high aspirations they could do so – although we only had a year to get them on track before they applied to university. That is what grammar schools do: only they have much more than a year to have that positive impact on students.

The evidence is that the combination of grammar schools and secondary modern schools (or technical schools as Kenneth Baker would prefer them to be called) can actually improve the life chances not just for those at grammar schools, but also for those at secondary modern schools. It’s time to end the prejudice against today’s secondary modern schools: look at the evidence.