Several years ago an acquaintance in England was assaulted by two thugs trying to rob him (he resisted), one with a knife, one with a razor blade. He ended up having around five hundred stitches. In the struggle he managed to stab one of the thugs in the leg with the knife while it was still in the thugs hand. He ended up being tried (and acquitted) for assaulting the robber. Really a deterrent to crime.
You're absolutely right, that is exactly the attitude of the Police and "Justice System" in Britain. They think that all citizens are just potential criminals waiting for an opportunity to break the law.
I actually had a long argument with a British liberal a month or so ago about whether or not women in US states with CCW were empowered to protect themselves from rapists if they exercised their right to carry a concealed sidearm. The idiot I was arguing with didn't think having a gun would make a difference to a woman who was attacked by a rapist and he disliked the idea of shooting a potential rapist, even just to inflict a minor wound as a deterrent. He thought it would be immoral to use armed force against someone to prevent a rape, mugging or burglary. This bloke is a science lecturer at a major British University. Unfortunately, we are dealing with extreme stupidity and/or brainwashing here.