I've got a different twist for advise to London.
Here in the US, we have plenty of inner-city shootings/murders/etc. However, the majority of those crimes are committed by thugs, and they are committed AGAINST thugs. Of course most of our thugs have no religion. If only you could get the muslim-ness out of your thugs in London, they'd just focus on killing other non-muslim-ness thugs!
But take away guns, take away knives, violent nuts are going to find something to kill people with. Cars, sticks, kitchen utensils, mechanics tools, they will find something. Why not just go to the end goal: lock everyone up in rubber rooms completely controlled by the mother gov't? Sounds like The Matrix!