WANDERING through Angell Town, a social housing estate in Brixton, south London, it is hard to imagine that it was once a notorious crime hotspot. A children’s playground sits opposite a row of bright modern houses with smart cars on the driveways. Teenagers kick a football around a new basketball court. Nearby, young mothers with children in buggies gossip in the alleyways, while the smell of jerk chicken lingers in the air.

Not long ago the place was a virtual war zone. “You wouldn’t walk into the estate, but if you did, you’d see people injecting in corners and prostitutes waiting for customers” says Donatus Anyanwu, the long-serving local councillor. The estate, which was built in the 1970s, was deteriorating by the 1980s. The warren of concrete underpasses and walkways made fine territory for muggers and drug dealers. The local council—“The People’s Republic of Lambeth”, jokes Mr Anyanwu—used it as a dumping ground for difficult tenants.

In the mid-1990s crime rates in Britain starting falling sharply, reversing half a century of increases. Violence, burglary, robbery and car theft are all less common than they were ten years ago. Partly, technological changes are to thank: car immobilisers and burglar alarms have reduced crime rates across the rich world (see article). But within the overall picture of decline a strange pattern is evident. Crime rates are falling faster in poorer inner-city areas than in the suburbs or the countryside. Estates like Angell Town are the most changed.

Data from the Crime Survey of England and Wales show that between 2001 and 2010 burglary rates fell by 43% in the most deprived areas, compared with a fall of 32% in the most affluent areas. Meanwhile, as Mark Simmons, Deputy Assistant Commissioner for the Metropolitan Police, puts it, “bits of outer London now look more like inner London”. Burglaries are up in suburban Barnet even as they have fallen in inner-city Lambeth (see chart). Croydon, on London’s southern edge, has also become more criminal: it suffered badly in the 2011 riots. An obvious reason for this converging trend is that high-crime areas had most scope for improvement, says Mike Hough of the Institute for Criminal Policy Research. Drugs and alcohol consumption have both fallen recently, which has helped places blighted by the drugs trade or by late-night alcoholic violence. CCTV cameras and better forensic technology have made trade much riskier for many criminals. A big increase in the prison population must have made some difference, though Mr Hough thinks it is probably small. All of these factors would be expected to have a stronger effect in poorer areas with more crime. But urban policy has had an effect too. As Angell Town residents attest, regeneration has helped. Dank underpasses and walkways have been closed off, ground floor garages converted to shops and a church, and the worst buildings demolished to make way for a mixture of social and private housing. That deters criminals directly and also helps to keep young, aspirational families on the estate. Meanwhile Lambeth’s population is changing as yuppies and new immigrants arrive. Since 2001 the borough’s white population has increased by 9% and its black African population by 11%. Some criminals may simply have moved out. Policing has changed for the better. Instead of merely reacting to crimes after they have been committed, neighbourhood teams hold meetings with residents and try to tackle social problems. According to Mr Simmons, as well as reassuring residents, this style of community policing improves intelligence-gathering and helps to convince witnesses to come forward, improving the conviction rate for gang leaders. Data-driven “hotspot” policing probably helped too, says Matthew Cavanagh, a former government adviser: police forces were ordered to concentrate resources on the worst-performing areas and to target the most persistent criminals, which naturally came at the expense of calmer suburbs.

Ominously, there are some hints that crime rates are about to start rising again. Since 2010 the number of burglaries has increased slightly, while in several London boroughs the number of street robberies is climbing. Police numbers are falling rapidly thanks to government cuts, and youth unemployment remains high. Inner-city estates like Angell Town seem to have built in some resilience. But perhaps next time the suburbs will bear the brunt of the crime wave.