It is not a row over nothing, as David Cameron protested, it is a row about something that couldn’t be more important. The argument over grammar schools is an argument about fairness, about equal access to education, and nothing could be more important than that. It is a row we do not have nearly as often or as loudly enough.

The grammar schools are the least of the problem. There are 164 of them in the country. Compare that with an astonishing 6,848 faith schools, about a third of all the schools in England. More than 6,000 of these are primary schools, overwhelmingly Church of England or Catholic, with a smattering of Jewish (37), Methodist (26), Muslim (8) and Sikh (2). And these are used ruthlessly by the middle classes as a barely covert form of social and academic selection. This is where the campaign for a fairer education system should be focusing.

Faith schools tie up places in good local schools for those families who are, or who are prepared to pretend to be, religious. They get the best results because they select their intake. Doing what the Blairs did and sending your children across town to a faith school has a direct impact on other children; faith schools prevent other four-year-olds, whose only fault is failing to have religious or hypocritical parents, from attending their nearest school, forcing them to travel sometimes miles from home each day, increasing their stress as well as addding to pollution levels.

Their admission criteria are opaque, manipulated and blatantly unfair, ranging from church attendance (twice a week for five years; every week for two years; whatever the governors fancy imposing) to academic record, parental committee work or, in one case, how many raffle tickets a child’s parents had sold at the primary school.

When schools are officially banned from selection on the grounds of race, colour, ability or parental background, the system sanctions selection on the entirely random basis of whether a child was born to a practising Christian family. And because faith schools set their own admissions criteria, and run their own admissions, in practice they can discriminate against anyone they choose. Many use their nurseries as a filter, so that a family effectively has to apply to the school when the child is as young as 2, and before any admissions code applies.

Questions about a child’s background were supposed to have been banned under the new school admissions code, with faith schools no longer allowed to seek supplementary information except about religion, or to interview applicants. One London school I know, a heavily oversubscribed Church of England primary, while technically sticking to the new rules, also asked this year for parents to send in copies of the child’s birth certificate with their application, ostensibly to prove their age – not something it is necessary for the school to check at that point. What the birth certificate also provides, of course, are details of the child’s parents’ professions. Parents with children at the school tell me it is overwhelmingly professional class – and pupils are drawn from surprisingly far away. Yet the school is surrounded by pockets of deep deprivation.

Schools can be fined or forced to reconsider an application, if a parent appeals successfully. One Church of England secondary for girls, Lady Margaret in Parsons Green, West London, was fined this spring for using unfair selection techniques after two families complained that their daughters had been unfairly refused places. The school operated a points system, rewarding attendance and primary school references as well as the extent of parental support. It also banded children by ability, ostensibly to ensure a comprehensive intake across the range but in fact using it to select higher ability kids. And it asked children to write an account of themselves and their home lives, which favoured articulate middle-class children. There was no clear rationale for the way governors scored the applications, the ombudsman said. To parents trying to apply for places at church schools, there never is.

Pressure from the Government to crack down on covert selection has turned the panic of parents unable to manipulate the system into near mania, with about 70,000 appeals being launched every year. More and more schools are expected to introduce lottery systems to allocate places in future, to ensure fairness and to prevent parents buying their way into the school of their choice by purchasing houses in the ever-tighter catchment areas. The unpopularity of the lottery system introduced by Brighton & Hove City Council this year contributed to Labour’s hammering in the local elections there in May.

It shouldn’t matter if schools choose to teach according to a particular religious ethos as long as they are open to anyone to attend and their entry criteria are fair. But in practice faith schools can also act as racial segregators. How many white Christian families, for instance, will choose to send their children to a Muslim school?

If you stop to think about it even for a minute, it is extraordinary that we allow publicly funded schools to exclude children simply on the basis of an accident of birth. How many four-year-olds even know if they are Christian? The reason for the lack of public outrage is because the system so strongly favours the aspirational and manipulative middle and professional classes who are the ones who would normally be making the most noise.

I am delighted that the Conservative Party leadership has ended its obsession with grammar schools. David Willetts, who declared the Tories’ love affair with grammars dead, is one of the truly great thinkers in public life, unafraid to turn dearly loved and entrenched assumptions on their heads. Now let’s see them turn their attention to the rotten selection processes of faith schools. Then again, a Tory leader who is assiduously trying to secure his own daughter a place at a C of E school, two miles and 46 alternative schools away from his home, probably isn’t the man to do it.

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