When and where to walk a dog off leash?

I was horrified by a report on UK TV Countryfile giving the statistics for the number of incidents every week when sheep and cattle suffer dog attacks, largely caused by people walking on paths alongside grazing animals, through fields of grazing animals...with their dogs off leash! It's totally unacceptable and irresponsible of the owner. I have no problem about a farmer shooting a dog which is worrying his grazing livestock.

Everyone should remember that their dog, whatever breed or mix, is basically a domesticated wolf and as such will always have hunting instincts. This is much stronger in some dogs than others, of course, but nevertheless, no one should walk their dog off leash near grazing animals.

Here's an article about training your dog to walk off leash