Focus on UK Metal Detecting: Artefact Hunting without Landowner's Permission

On a metal detecting forum near you is a discussion of the "problem" of "tennant (sic) farmers". Member "craghopper" (Thu Nov 21, 2013 12:01 am) started it:

"Just read about detectorists losing their permissions because the farmer is a tennant and the land is council owned and they don't want detecting on their land, I wonder how the council found out.

As if the landowner should not know what is happening on their own land. There is a name, isn't there for metal detecting on land when you've not got the proper permission. It seems this is not an infrequent occurrence in UK metal detecting.  Member Tony Hunt (Thu Nov 21, 2013 10:40 am) tells of a case in "Dorset fairly recently" where a Treasure award  (a large hoard of axe heads) went to the landowner and not the tenant farmer who had given the search permission "The finder obviously lost his permission through everything turning sour". Member geoman (Thu Nov 21, 2013 11:57 am) tells a salutary story:  "i know of one detectorist who was not challenged by the actual landowner, but had a visit from the Police so be warned".