Trespass to land is a civil wrong and as such the police have no jurisdiction. Under common law, the landowner has a right to re-entry on the land, however the ejection of the trespasser is fraught with danger for the landowner. Initially, the landowner should ask the occupier to leave the land and if he/she does then all is well. The problems start however, if he/she refuses to leave the land.
The owner of the land could commit several criminal offences if he forcibly removes the trespasser and his/her property from the land. The best and safest course of action is to obtain a court order, which if breached may then turn into a criminal matter.
If the police do attend an incident such as this, they are merely there as observers for any possible criminal offences committed by either party. The police cannot assist in the removal of the trespassers or their property from the land in question.
The police do have some powers against larger groups of occupiers if damage has been caused. Trespass is very complex and guidance should be sought where appropriate.
Taken from Police national legal database
I thoroughly enjoy reading the 28dayslater forums, it's something that me and my friends find very interesting, as a lot of us are into photography I guess the interest stems from there. As I said earlier on the pictures you got at Alton Towers are awesome, really well done.
I have been reading up on Urban Exploration for a while now, and I think I've just about grasped the issues surrounding trespassing, one question I would have, which I just thought about earlier today actually, is what is the issue when there is a sign saying something along the lines of "Trespassers will be prosecuted". I don't know but I may have seen one of these at Alton Towers. Just curious :)