THERE is a reason why the Archbishop of Canterbury came unstuck over church-school admissions last week, and it was only partly because his guard was down during a brief but wide-ranging interview with a news-hungry journalist. It was the same reason why the Bishop of Oxford came unstuck in 2011, shortly after he had been appointed chairman of the Church of England's Board of Education. School admissions policy is complicated and political. A church spokesman, assuming he knows his brief, can deal with one of these factors, i.e. something that is complicated but uncontroversial, or political but simply expressed; but the combination of the two is an accident waiting to happen.

The myths are legion: churches dangle school places in front of young couples in order to boost congregation numbers; church-school heads engineer the entry in order to select the best-performing pupils; the system is easily manipulated by pushy middle-class parents (this criticism usually comes from unsuccessfully pushy middle-class parents); the Church has a stranglehold over schools in order to indoctrinate children; and so on. First, half of church schools are voluntary controlled, and thus adhere to the local authority's admissions policy. Second, those schools that have a degree of leeway - voluntary aided and academies - must none the less follow the Department for Education code. Third, far from attempting to manufacture a comfortable, monochrome school population, some church schools use the limited freedom they have to deviate from a purely geographical set of admissions criteria in order to combat the effects of being in a middle-class area.

It was entirely understandable when Bishop Pritchard pondered, in 2011, the possibility of a ten-per-cent faith-based quota; and when Archbishop Welby last week reported, approvingly, "a steady move away from faith-based entry tests". But it is also understandable when church-school heads ask how they are to maintain their Christian ethos without a ready supply of Christian teachers or at least a smattering of churchgoing families. The temptations to favour bright children from involved families remain, but many school heads point out that managing admissions to an over-subscribed school is as much a burden as a privilege. Turning people away is never good for mission.

The new figures comparing church-school performance with non-C-of-E schools - four per cent more "good" or "outstanding" ratings from OFSTED - suggest that the Church has got it about right. A narrower gap might hint that church schools have nothing extra to offer. A wider discrepancy could signal that church schools are not as involved with the worst-performing pupils as they should be. Perhaps these figures, and the indications that church schools have roughly the same ethnic mix and need for free school meals as their community-school counterparts, will silence some of the critics.