well i found out what happened so hows this for bare faced cheek. A guy and a teenager drove into the allotment in the morning (which most people dont do) and then proceeded to dismantle the whole thing, leaving a pile of nuts and bolts which i found today. The two guys on the neighbouring plots were there and thought it a bit funny, but thought as they were doing it at that time and so well prepared with spanners etc that they must have had permission to do it!
Bastards!
Bastards!