I have seen this very imposing prison many times, I once camped just up the road and looked down on it in the middle of the night, it sends a chill through you!!!
It always used to be patrolled by police on horseback but they don't seem to do that now!
I also once got told off by the prison police for leaving my car unlocked in the village of princetown whilst in the cafe having a cuppa.
http://freepages.history.rootsweb.com/~cyberhe ritage/moors/pris1.jpg