it was, said Lord Baker, “the fastest U-turn in political history”. As the dust settles on the Government’s policy reversal over quotas for faith schools, it is clear that legislating on religious integration is like walking blindfolded into a minefield.

So why did Alan Johnson risk the wrath of Catholics by proposing to enforce quotas at new faith schools, only to abandon them rapidly when confronted by their powerful lobbying machine?

We need to go back to 2001 and the Cantle report in the North. It highlighted how schools reinforced segregation and recommended that faith schools, and others dominated by one ethnic group, should take a quarter of pupils from other backgrounds.

Yet only months earlier Labour’s manifesto had been gung-ho: “We will encourage more church and other faith-sponsored schools where parents wish it,” it said.

Responding to Cantle, the Government said it could not oblige faith schools to take pupils of other beliefs. “Nor would we want to,” a spokesman added.

Then the London bombings changed everything. Ministers realised that faith schools could reinforce segregation. Two favoured policies clashed: the desire to unleash parent power and to avoid segregation. It was the seed of Mr Johnson’s U-turn.

There are eight state-funded Muslim schools, with three more in the pipeline. But Whitehall estimates that there are a further 41 independent Muslim schools, although some say the figure does not include numerous very small schools.

In practice, the 25 per cent quota was never going to affect Muslim schools as there is no evidence of non-Muslims clamouring for admission. When this sank in, ministers realised they were risking electoral backlash from the Catholics for a policy that would leave their real target unaffected.

But are faith schools any more divisive than neighbourhood comprehensives where the distance criterion reinforces housing segregation and sorting by mortgage?

Research from the National Foundation for Educational Research has found that voluntary-aided secondaries admit pupils who are slightly more affluent and less likely to have special needs than the average for the immediate neighbourhood. This suggests, on top of sorting by religion, an element of covert social sorting. But Anglicans and Catholics insist their schools take many pupils of other faiths - the Catholics claim 30 per cent from other faiths.

Yet integration is patchy: research by the London School of Economics found that only 46 per cent of faith schools in London made specific mention of “other faiths” in their admissions criteria.

If enforced integration is out, what else can be done? A practical approach is partnerships between schools of different faiths, involving pupil and staff exchanges. As the number of faith schools looks set to grow, the Government may need to find ways to encourage such partnerships.

Mike Baker writes about faith schools for BBC News Online

Who goes where?

Thirty per cent of state schools are religious: Church of England 4,646; Catholic 2,041; Jewish 36; Muslim 8; Sikh 2; Greek Orthodox 1; Seventh Day Adventist 1 October 3: the Church of England volunteers to admit a quarter of pupils from other faiths in new schools.

October 26: the Government drops plans to give local authorities the power to enforce a 25 per cent intake of “other faiths” at all such schools.

Roman Catholic schools have more black pupils but fewer Asian pupils.