Comment: knives out

There are solutions to these problems, if the authorities are prepared to be tough. The Mayor has already committed to greater use of scanners and random searches on the transport system. There will be the usual claims that stop-and-search victimises black and poorer teenagers, as voiced by the Children's Commissioner, Sir Al Aynsley-Green, at the weekend. Sir Al's intervention is deeply unhelpful: few people whose children have to risk such violence are likely to see it that way.

But it is not enough for police to detect and disarm more knife-carriers: they also need to prosecute them. As this newspaper highlighted last week, despite increased penalties, conviction rates against those who carry knives are pitifully low, and the proportion given custodial sentences even lower. The police and the courts now have substantial powers and stiff penalties with which to deter or punish the thugs; Transport for London can stop disruptive teenagers travelling for free. For all our sakes, it should use its powers to the full.