I don't know if the Tony Martin case in itself was the demarkation line or if it simply reflected a breakdown in society, but from living in the countryside since 1970 I do know that prior to the publicity surrounding the incident, farm break-ins, here anyway, were quite rare.
The understanding was simply that farmers have dogs and farmers have guns. That In itself was a deterrent.
The fallout from Tony Martin effectively removed that deterrent from the collective minds of the lowlifes who then seemed to gain a new boldness.
Initial criminality thereafter was usually limited to the theft of Quad Bikes, chainsaws, power tools or anything that could removed relatively easily.
As the law now seems to have largely given up on enforcing such matters, subsequent criminality has progressed to stealing farm vehicles, thousands of litres of heating oil and violence.
As most farms are some distance from any potential law enforcement response times and the number of available Officers has been cut, the future is not looking good.