Your can deter the herding by (gently) moving into the dog's space to back him up. The same way that the dog moves the sheep.
The dog is attempting to control people in the same way that he controls the sheep. People of course should be control of the dog.

Greentrees' Top Royal Escort - DYLAN HIC, CGN, CD, FDN
Texanda's Montrose - MONTROSE (aka Monty) HIC