Some years back I also decided to have a close look at a VOR - Pole Hill as it happens as it is the closest to me. As I remember it, it looked exactly like the pictures above, but what I remember most was a police car drawing up within a few minutes of me climbing over the fence. I thought I was going to be in some trouble, and wasn't prepared for this, but my innocent explanation that I was just "interested in these things" seemed to be accepted at face value. In the light of the World Trade Centre incident I cannot see this being the case anymore.
I haven't been back to Pole Hill since - it is a bit remote on the Pennine hills, but back then it was all too easy to access. I would like to think it is a bit more substantially protected now, although I never knew whether the rapid arrival of the police was just the result of a fortuitous passing, or followed some form of active monitoring.