The British war on knives is a fool's errand. A normal steak knife is cause for arrest. Its blade is longer than 3 inches. If you carry a knife you could cut up a steak with, you are bound for a "stop and search" arrest.
All the guns are gone, having been banned. Knife crime is the result. If the Brits are successful in ridding their nation of knives, rock control will come next.
Imagine being whacked in the head with a 10 pound rock!