"For some farmers", says a vacant woman in a farming programme on the BBC, "metal detecting can be a lucrative diversification" (4:09 here). So can selling their daughters into prostitution, the NFU would recommend getting agreements on how to divide the cash in at least one of these cases.
See Heritage Action on this ('Yuk'). What is the BBC thinking of? No doubt the programme's producers will be getting a stiff letter from the PAS pointing out the irresponsibilty of propagating such an attitude to the archaeological heritage among farmers, of all people.