Our place won't even let you in the yard unless you are clearly a member of the public with a few bits, or if its trade, it must be a marked vehicle with company logo.
You have to sign to say it is your stuff/show ID, plus they take a photo of you with your vehicle and contents.
We had a big rell of phone cable kicking around the place, tiny copper wires, not worth stripping. Gave it to the pikeys. 30 mins later, i got a phonecall from the police, they had stopped said pikes and seen the cable; had a sticker on with my name and number on. Cops wanted to confirm we had given it to them.