Winchester Whisperer in her comment in the previous post wondered if the shepherds would have worn smocks. In this picture taken in 1876 at the First International sheepdog trials at Alexandra Palace in London, you can see that the attire was not very different from 1973 or today for that matter. The hats have been replaced by flat hats/caps it would seem.
The picture is a bit small. Click on it to enlarge it slightly.