It was the start of the walk and he always goes off the lead (we live in a town).
He has a very strong prey instinct, and yes he would have worried the sheep. He doesn't know what to do with prey when he gets to it though (the poodle in him takes over), but I would have been 100% in the wrong if I had have had him off the lead and in the highly unlikely event that he took down an animal.
NEVERTHELESS, however thoughtless or unaware an owner, shooting a dog is NOT an acceptable response. It's just not. And no, I'm not on a wind-up. It's a f***ing outrageous overreaction, and people who give a knee-jerk 'bloody serves 'em right' type response to the question might be advised to wind their necks in a little and reflect.