THE poorest people in Leicester by a wide margin are the Somalis who live in the St Matthews housing estate. Refugees from civil war, who often passed through Sweden or the Netherlands before fetching up in the English Midlands, they endure peeling surroundings and appalling joblessness. At the last census the local unemployment rate was three times the national average. But Abdikayf Farah, who runs a local charity, is oddly upbeat. Just look at the children, he says.

Close to Mr Farah’s office is Taylor Road Primary School—which, it turns out, trumps almost every school in Leicester in standardised tests. Its headmaster, Chris Hassall, credits the Somali immigrants, who insist that their children turn up for extra lessons at weekends and harry him when they seem to fall behind. Education is their ticket out of poverty. Poor district, wonderful school, well-ordered children: in Britain, the combination is not as unusual as one might suppose.

Britain has prized the ideal of economically mixed neighbourhoods since the 19th century. Poverty and disadvantage are intensified when poor people cluster, runs the argument; conversely, the rich are unfairly helped when they are surrounded by other rich people. Social mixing ought to help the poor. It sounds self-evident—and colours planning regulations that ensure much social and affordable housing is dotted among more expensive private homes. Yet “there is absolutely no serious evidence to support this,” says Paul Cheshire, a professor of economic geography at the London School of Economics (LSE).

And there is new evidence to suggest it is wrong. Researchers at Duke University in America followed over 1,600 children from age five to age 12 in England and Wales. They found that poor boys living in largely well-to-do neighbourhoods were the most likely to engage in anti-social behaviour, from lying and swearing to such petty misdemeanours as fighting, shoplifting and vandalism, according to a commonly used measure of problem behaviour. Misbehaviour starts very young (see chart 1) and intensifies as they grow older. Poor boys in the poorest neighbourhoods were the least likely to run into trouble. For rich kids, the opposite is true: those living in poor areas are more likely to misbehave.

The researchers suggest several reasons for this. Poorer areas are often heavily policed, deterring would-be miscreants; it may be that people in wealthy places are less likely to spot misbehaviour, too. Living alongside the rich may also make the poor more keenly aware of their own deprivation, suggests Tim Newburn, a criminologist who is also at the LSE. That, in turn, increases the feelings of alienation that are associated with anti-social conduct and criminal behaviour. Research on England’s schools turns up a slightly different pattern. Children entitled to free school meals—a proxy for poverty—do best in schools containing very few other poor children, perhaps because teachers can give them plenty of attention. But, revealingly, poor children also fare unusually well in schools where there are a huge number of other poor children. That may be because schools have no choice but to focus on them. Thus in Tower Hamlets, a deprived east London borough, 60% of poor pupils got five good GCSEs (the exams taken at 16) in 2013; the national average was 38%. Worst served are pupils who fall in between, attending schools where they are insufficiently numerous to merit attention but too many to succeed alone (see chart 2).