A while back I saw a film of the merino sheep gathering in New Zealand...totally amazing! Something like 10,000 sheep (? ) and herders were helicoptered to the mountaintops ..I seem to recall the helicopters did some of the herding but I might have made that up.
As for the John Wright song about the collie, first i have to find my cds - not sure if it is on cd, maybe I only heard it live in concert?   Think it was about a shepherd no longer needing dog due to (would it have been foot and mouth? Do sheep get that? Or other ecconomic decline..) it is so sad - and John had worked as a shepherd, so it was very personal.....