One thing that dog owners seem unaware of, Control of Dogs Act 1937, which states that ALL dogs MUST be kept on a collar and lead when in a public place. Failing to do so is an offense. As I understand it, dogs found attacking sheep can be legally shot, shame you cannot shoot the owners.
The vast majority of attacks blamed upon Foxes, is in fact the work of stray dogs. Over the years I have noted this;- A fox can walk through a flock of sheep, and they hardly lift their heads from grazing, BUT, let a strange dog in there and it's instant panic .... what does this tell us ?
I fear that it's time farmers and smallholders took on a zero tolerance policy with strays, it's not the dogs fault, that is the nature of the animal, but dog owners must be forced to accept their responsibilities.