Fifty years ago, the Labour government invited local authorities across England, Scotland and Wales to submit their plans to end selection in schools and introduce a new comprehensive system. Instead of dividing children into the academic and non-academic at 11 years old, the new ideal was to be based on non-selective schools serving everyone in the community. The founding principle was that that every pupil, whatever their background, would receive the same standard of education.

This week a conference at Edinburgh University will be discussing whether the system has lived up to those ideals, but any attempt to judge comprehensives has to be put into the proper context. The Wilson government may have set out 50 years ago to devise a system that would educate everyone, but from the off that is not what happened. Around 95 per cent of pupils are now educated in comprehensives but two other systems continued to exist alongside comprehensives: independent schools and Catholic schools which were comprehensive but could specify entry criteria. In other words, from its conception, many thousands of pupils were excluded from the comprehensive system which has necessarily impacted on how it might, or might not, have worked.

Subsequent developments have also served to put some pressure on the comprehensive premise. The right of parents to put placing requests to a school of their choosing, for instance, has made it harder for some schools to thrive; many parents – as is their right – also choose to move to a particular postcode because they would like their children to attend the local school. These are freedoms that should remain, but we have to acknowledge that they are also freedoms that have an effect on the equality of comprehensives.

Given those caveats, how have comprehensives performed over the last 50 years? There are certainly some who would argue that the system has failed because it does not serve the very poorest and there are some parents who feel let down. As The Herald reported at the weekend, one group of parents in Milngavie is drawing up plans to run their own school after East Dunbartonshire Council decided to shut down St Joseph's Primary.

But, in the end, the report card on comprehensives has more positives than negatives. Education is less divided than it used to be, many more children are achieving many more Highers and many more are going to university. Whatever their background, all children also have access to the same curriculum and their school will be inspected and told to improve if it is not up to scratch. Comprehensives have achieved much of what they set out to achieve five decades ago.

None of that means we should call comprehensives a success and move on because there is still an attainment gap between the poorest and best-off children and the poorest are still shockingly under-represented at university. To some extent, comprehensives will only ever be one part of the solution, as the inequalities in school to a large extent reflect the inequalities in wider society which schools are powerless to control. But if the system created 50 years ago is to thrive, it must be subject to constant review to ensure that it is still based on those founding principles: that schools should serve everyone in society and that all children should receive the same standard of education, whatever their background.