Britons who have held burglars in their homes until the police arrived, by using toy pistols, have been arrested along with the burglars. To the collectivist mindset, independent self-help of any sort is a threat to their vision of the government as the sole source of protection and direction.
If someone attacks you in Britain and you knock him down, you are not allowed to hit him again or you will be charged with assault. Apparently they think that someone who has been knocked down is now harmless. People who have led sufficiently sheltered lives may believe such things -- and impose such notions on others through the power of government.
The British Broadcasting Corporation (BBC) has even advised that you are not to yell "help" when you are attacked in a public place. You are to yell "Call the police."
Both self-defense and coming to the aid of others are lumped together as "vigilante" actions.