“A S CASES OF sexual abuse with which the courts have to deal, this case comes top of the scale,” said Geoffrey Marson QC as he passed sentence on October 19th. Yet the crimes in the northern English town of Huddersfield for which 20 men were convicted followed a pattern that is now all too familiar. Between 2004 and 2011 the men raped and abused at least 15 girls, some as young as 11, often at parties where they were subdued with drugs and alcohol. All of the abusers were Asian, primarily of Pakistani origin. Their victims were vulnerable, mostly white girls, some from care homes. One had the mental capacity of a seven-year-old. Each was first “groomed” by a man who gained her affection with gifts and attention. Threats then kept them in the cycle of abuse that followed.

In the past seven years, similar child-grooming gangs of mostly Asian men have been jailed in more than a dozen towns in England. Some of the crimes date as far back as 1999. “These sick Asian paedophiles are finally facing justice,” tweeted the home secretary, Sajid Javid—himself of Pakistani descent—when the latest verdicts were announced. His comment drew a mixture of condemnation for its racial charge and praise for saying what politicians and officials have sometimes considered unsayable.

A large majority of those who sexually abuse children in Britain are white men. But there is some evidence that Asians are over-represented among the offenders. In an analysis of patchy police records from 2014-15, about 60% of child-sex offenders were white and 12% were Asian (20% were of unknown ethnicity). Of the population at large, whites made up 86% and Asians 7.5% at the most recent census, in 2011.

Asian men seem to be particularly over-represented in some forms of group-based sexual abuse. According to a study in 2011 by the Child Exploitation and Online Protection Centre, a police agency, nearly a third of those suspected of abusing children outside a family, professional or online setting operated in groups. Most such groups were of a single ethnicity, the most common being Asian. When all suspects in such cases, including solo offenders, were considered, 30% were white and 28% Asian (the ethnicity of 38% was unknown).

Nazir Afzal, a former chief prosecutor for the north-west of England, says white offenders who operate in groups tend to carry out abuse alone, sharing their victims’ details with other members of their circle. By contrast Asian group-abusers are more likely to socialise and commit abuse together, which makes them more visible.

The details that emerged from Huddersfield were, as in past cases, damning of the authorities. The parents of one of the girls said their plea for help was ignored because their daughter refused to file a complaint, which is common among victims controlled by their abusers. Ten years ago, says Rick Muir of the Police Foundation, a think-tank, the police focused on visible crimes such as burglaries or rowdy behaviour. What took place behind closed doors was more likely to be viewed as a matter of personal choice. Child-sex investigations focused on abuse at home. The term “child prostitute”, which implies choice and consent, was official.

Some of these mistakes have since been corrected, which is partly why old crimes are being unearthed. Police forces now have specialised units for child-sex crimes, which work with social workers, teachers and doctors to identify children at risk. But for the victims in Huddersfield, and the other places where similar trials are likely to follow, this is all too late.