funnily enough if you get pulled by the police in your car (say for example a brake light isn't working) and they additionally spot a knife in your car, you need a good reason to have it, otherwise they take you to court for carrying a knife in a public place
also a restricted amount of guns are allowed to be owned and used in the uk, there is already a system in place for background checks and gun registration. however, there are no open carry laws/self defense stuff (killing other humans :O), and if your gun is used to commit a crime you are held responsible. there's a load of other stuff too, like needing to keep all your stuff in a safe, and telling the authority about amount of ammunition you have iirc.
the uk just doesn't have the gun culture which america has.
