It is Easter and, for once, Britain's churches will be well attended. For most of the rest of the year, they struggle to fill the pews. On a typical Sunday, only 6 per cent of the population go to church. In London, however, though the percentage declaring itself Christian is far below the rest of the country, the proportion is 8 per cent.
How come? One reason, I suggest, is the highly competitive London schools market. The revised admissions code, if anything, strengthens the role of church attendance in securing a school place, since other forms of selection are now banned.
That's good news for the churches: without the incentive of places at sought-after state schools, they would find it even harder to attract customers, particularly from younger age groups. School places perform the same function for them as free DVDs perform for the weekend newspapers.
Churches, like other organisations, have premises to maintain and employees to pay. They wish to protect and expand their markets. When almost everybody went to Sunday service, placing pennies in the collection plate, the churches could run schools for the benefit of the poor. It is not cynical to suggest other considerations now take precedence.
The problem, as TES readers will know, is that the schools' freedom to select their entrants leads to various forms of discrimination and thus to a partially segregated education system. The most obvious discrimination is ethnic: children of Pakistani and Bangladeshi origin, being overwhelmingly Muslim, will rarely get to church schools. Families of African and Caribbean origin are often devout Christians, but many worship at Pentecostal churches which, while not ruling them out of admission on religious criteria, places them at a disadvantage.
There is also social and academic discrimination, which is less obvious. In London's faith schools, academics found, only 17 per cent of pupils qualify for free meals and only 19 per cent are of low ability, compared with 25 per cent and 31 per cent respectively in non-faith schools. The figures cannot be explained by location: if they reflected the social composition of their neighbourhoods, faith schools would educate many more children on free meals.
The most recent research - by Rebecca Allen, of London University's Institute of Education - suggests that, across the country, religious schools may have as many as 50 per cent more top-ability children than community schools located in neighbourhoods with the same demographics.
How does such discrimination occur?
Suppose a family attends church only a couple of times a year and donates pound;1,000 to the church roof fund. Will the vicar deny them support if they apply for a school place?
That is perhaps an extreme example. What more commonly gives advantaged families the edge is that they are more likely to have the commitment and discipline to drag their children to church every week, and make themselves known to the vicar.
Moreover, disadvantaged families tend to avoid schools that are "not for the likes of us".
If you were looking for a proxy that allowed you to recruit the less problematic children, church attendance would do a decent job. You will, to be sure, get some low-ability children from low-income families, but not the real basket cases.
Nobody need set out deliberately to exclude particular kinds of children. It is simply a result of how the system works.
That is why I doubt the new admissions code can end segregation. It is human nature for parents to want their children to attend school with peers from similar backgrounds, and for schools to want children who are easier to teach. Successive governments, by making education more competitive, have accentuated those instincts. Social and academic selection if stopped in one form will arise in another. That has been going on ever since grammar schools were abolished.
Peter Wilby is former editor of 'New Statesman' and 'The Independent on Sunday'.