Ive recently had trouble with people (kids as far as i know) coming
into my back garden and causing trouble. My house backs onto a council
garage area and my drive (to the rear) is currently open to the road
and the rest of the garden only had a 3 foot wall round it.

I have now just about finished enlarging the wall to 6 foot and am
about to make some big gates.

If i wanted to put something sharp spikey and painful on the top of my
wall or gates where do i stand? Are there any legalities involved in
this?

I dont want to get in trouble because some little scrote cut his hands
open trying to climb over my wall.

Can I just do as i like?