Well can the innocent really win?
If you put up barbed wire/razor wire and a good fence, some parent is going to complain about it, I guess the council will then come along and make you take it down. The very next day some kid will walk onto your property climb up on your roof, fall and sue you for not making your property criminal proof.
Lets get it straight then, you have the choice of a claim from the thief/ trespasser injuring himself on your fence whilst gaining entry, or making a claim from injuring himself if he's successful at getting in.
Which is it to be!