Tories - "Anyone caught carrying a knife without a good excuse should expect to go to prison, Tory leader David Cameron says"
Labour - "teenagers arrested for carrying knives may be forced to visit victims of fights in hospital"
The problem is not teenagers carrying knives - the number has almost certainly gone down considerably in the last 50 years (I would imagine that most Scout jamborees in times past featured about 30,000 teenagers and men all wearing knives on their belts). It's the propensity to use them that's risen.
If Cameron gets his way we'll see the same sort of thing happening as happened with mandatory sentences for guns - retired head teachers, hikers and the like being banged up as police and prosecutors pick the low-hanging fruit.
One of my biker friends - a big chap with very long hair - always wore a large knife on his belt. Never stabbed anyone. They're useful things if you lead an outdoor life - and he did, always off camping or to festivals with the tent on the back. When I moved out of London he helped me move my things in his old Transit. On the way to my Streatham residence he stopped in a Clapham pub for a beer and half the bar emptied !