Nothing has made them angrier over recent years than seeing a previously good neighbourhood comprehensive being undermined because distant grammar schools or others with an element of selection were suddenly allowed to entice the brightest children.
Fervent believers in market forces have managed to create the myth that greater parental choice will improve overall educational standards, and even Labour politicians now naively accept this.
But giving people choice is by no means always a good thing, Letting some parents - those with intelligent or talented children - send their offspring to a school of their choice destroys comprehensive education and blights the educational chances of millions. Comprehensive schools bereft of bright students are nothing more than the previously familiar, inglorious secondary moderns.
Another current myth is that comprehensive education is ineffective. Steady improvements in examination pass rates since the large-scale abolition of the 11-plus give the lie to this. My own children's A and B grades at O-level and A-level, and the many good results obtained by pupils in the comprehensive schools in which I taught for 11 years (after seven years in a grammar school), have repeatedly proved to me that comprehensive education can work very well.
There are also the results from Scotland, where pupils outperform the rest of the United Kingdom. The Scots got ahead by adopting comprehensive education almost universally 20 years ago, but now even their system is beginning to show signs of damage through parental choice.
Blind faith in market economics led to the widening of choice which most parents never wanted and thereby to the undermining of the still developing educational system which the majority approved of. Hence increasing numbers of potential voters with bright children are now finding themselves in catchment areas of schools that are effectively secondary moderns, and they are not keen to entrust their children to them.
Politicians who have become aware of their plight and are keen to secure their votes hope to appease them by guaranteeing continued choice and more academic selection. The end of the comprehensive era is moving ever closer, as is the prospect of worsening failure at the lower end of the ability range. By trying to fix what was not broken, politicians are causing some really worrying problems.
The demise of the comprehensive system can only give greater impetus to the most unattractive of recent middle-class tendencies, that of trying to isolate themselves and their children from the rest of society. Sitting next to someone less privileged than oneself is something that not just the odd Tory minister now wants to avoid.
This approach, like many modern philosophies, has come to us from the other side of the Atlantic. The United States can already show us what kind of society this may lead to: the more privileged retreating behind high walls and barbed wire by choice, 1.6 million kept behind them against their will, and much of the rest either anxious or envious.
The comprehensive system can not only deliver good education for all; it seems to be the only means so far invented that can possibly help us to avoid the social problems that already bedevil the United States.
It has certainly raised overall educational achievement far beyond levels reached in the bad old days of selection. That is why the system should be made more truly comprehensive and improved, instead of returning to selection.
Some may decry the attempt to create an effective comprehensive system as "social engineering", but so is every other kind of educational provision: this is at least one that no one need be ashamed of.
The minority of parents with able children who want to create special niches just for their own kind and thereby effectively destroy the whole system should not be indulged. If they insist on special provision, they should have to pay for it, but before they do they might like to know that a comprehensive school with a wide social mix got both my children to Cambridge. If we really want to give children equal educational opportunities we should scrap all other fancy schemes and concentrate on the restoration, preservation and expansion of the comprehensive system.