Proving that if you ban anything from law abiding citizens you only hurt law abiding citizens. London's law states "It is illegal to: sell a knife of any kind (including cutlery and kitchen knives) to anyone under 18. carry a knife in public without good reason – unless it's a knife with a folding blade 3 inches long (7.62 cm) or less, eg a Swiss Army." Just carrying a knife on your person is illegal in London, yet these attacks continue at alarming rates.
Criminals don't obey the law, only law abiding citizens do. Limiting the ability of law abiding citizens the right of self defense is criminal. Typically police don't protect, they can't always be there to protect. Police typically only report as they show up after the crime has been committed.
https://www.thesun.co.uk/news/5981153/mile-end-stabbing-attack-walthamstow-london-latest/