I think it will depend on how good your council are at checking up on these things. I have worked in a few CT depts in my time, and apart from an annual review of the discount, and following up leads of potential false claims, there isn't any fantastic information sharing system that would pick it up.
I have dobbed someone in before, some people down the road were constantly having parties. I checked their account and noticed they were claiming it when there were 2 people living there, so it got taken off. Made me feel a bit better, the parties stopped as well!!