I blame the farmer for misleading the fox over the chickens! If you prime instinct is to hunt for food, and you find a load of chickens trapped in a cave (which is probably what the fox thinks a hen house is) then it is going to think all it's Christmas's have come at once. It is tragic that farmers loose out, but there are better ways of dealing with the fox population than to hunt with a pack of dogs. I too worked on a sheep farm, I have also worked for landowners, including those grouse shoots, so I know how bad the problem of vermin can be, I also know that packs of dogs are not the only solution!