A spate of knife killings in the United Kingdom, largely of young Londoners, has prompted outrage in the media, fear on the part of citizens, and new policy proposals from government. According to the authoritative British crime survey, weapons were used in around a quarter of violent incidents in England and Wales in 2006-7, although the survey does not take account of crime affecting people under 16 years.1 According to this source, the annual prevalence of knife use has remained constant at around 7% of all violent incidents since 2000. Hospital episode statistics show that rates of hospital admission in England after violence of all types increased (from 82.7/100 000 population in 2000-1 to 114.4/100 000 in 2006-7) at almost exactly the same rate as admissions after knife violence (from 8.5/100 000 to 11.3/100 000). In contrast, rates of treatment in emergency departments after violence of all types decreased from about 850 to 620 per 100 000 over the same time2; no national emergency department data are available on knife violence specifically. In summary, since 2000, violence in England and …