This exchange between Brian and P.C Clarke in the first season, discussing a security guard wounded in a robbery connected to a case, something of which has piqued Brian's interest:
Brian: If you were robbing a security van and wanted to immobilise the guard inside, where would you shoot him?
Clarke: ... The head?
Brian: ... You'll notice, Clarkie, I said 'immobilise', not 'kill instantly in an unnecessary bloodbath'.
Clarke: ... The leg.
Brian: The leg! Good! Leg.
Clarke: Or the foot.
Brian: Let's just stick with the leg.
Clarke: [Eagerly, getting a bit carried away] Both legs.
Brian: [Exasperated] One leg would probably suffice!
Clarke: But two to make sure.
Brian: It's a thirty second situation, Clarke! You shoot a man in the leg, he's really not going anywhere.
Clarke: But if you've already shot him in one leg, he's kind of stuck in situ while I shoot in in the other one. Might as well. Bang, number one — he can't move. Bang, number two — he really really can't move.
[Brian is utterly lost for words for a moment]
Brian: ... Get your coat, son.