Knife Crime: Ineffective reactions to a distracting problem? – A review of evidence and policy / Centre for Crime and Justice Studies, 4 Aug 2006

PDF - http://www.kcl.ac.uk/depsta/rel/ccjs/knife-crime-2006.pdf
"Says that there is a lack of knowledge about the carrying and use of knives and the motivations for this behaviour. Furthermore, there is insufficient evidence that a knife amnesty or harsher sentences for carrying knives and knife-related offences will decrease the level of knife use and carrying. "