Uhm sorry to push the post back on topic...but to get back to the being kicked off land for detecting...my bf was detecting a schoolyard in the summertime, was told by a friendly cop that NOBODY could be on school property when it's closed. Someone who used to let him detect on his property revoked permission (he also revoked permission for me to use the old house on the property for photo shoots...damn) as his daughter was getting the house and would be living there, and she had decided she was going into MD'ing too!
Another what-can-you-do scenario. A buddy of bf knows someone who used to own an old hotel that has since been torn down; bf expressed interest, via his buddy, in detecting the site; owner of site was 'OMG what if he finds a quarter?' Buddy didn't know what to say, so no permission there!!!
Now, I can offer one pretty much surefire way to get permission to detect private property: get a woman to ask!! Us helpless l'il females (lol I'm 5'10 and no weakling) are awfully good at batting our lashes,smiling sweetly and asking nicely. If the place is also really scenic I will ask permission to go shoot buildings, livestock etc. (I used to train horses so I know my way around critters, so if need be I can yakk awhile about horses/cows/poultry/emus/alpacas etc) reassure them that I realize the risks I am taking and will not hold them responsible if I get hurt....then add, oh, btw, my bf likes to search for historical artifacts...would you mind if he looked for some on your property? And he digs small holes and fills them back in.
You'd be amazed at how well this works!!!