In reply to GirlieEyes:
I believe it is a specific offence to climb on a listed building. I was once acosted by the police when climbing on the highstreet face of Queen's college in Oxford. [context, at the hight of the animal right's protesters attacks on Oxford University]
"What were you doing up there?" asked the policeman
"climbing"
"But why were you"
"because it was there"
"errr... what?"
Apparently I could have got an £80 fine, but when they realised I was actually just climbing because I was a climber, rather than some drunken student showng off/animal right's protester trying to burn down the university they let me go on my way...