He's probably thinking back to the farmer who was originally charged for shooting two people who broke into his home.
The way the law system works here is not whether you can defend your home but how much damage you inflict.
If I was at home and someone broke into my house I could give them a warning to back off and failing that I could beat the shit out of them until they left the home but I must Not block them from leaving or hold them captive.
You can either scare them off with a beating or do what's known as a citizens arrest which you ensure both yourself and the other person/s safety whilst calling the police.
In short it's the same principle as giving first aid, if you know what you're doing go then ahead but if you don't then don't fucking try because you'll make things worse.
E: Also Limited's from Dorset, no one ever bothers listening to people from Dorset.