Herdwicks? Just come round a bend in the Dales and meet a flock of Swaledales. These are the ones that chase sheepdogs (in fact they gave mine some grief before she decided she'd had enough and put them in the corener of the field). The sheep here are just stubborn, or is it just plain thick?
One flock of Herdwicks saw me (and dog) come over the hill and then decided to leg it - we must have been at least a quarter of a mile away. That's Cumbria for you.
Belgian Blue cattle or Limousins would make the best roadblocks, you wouldn't want to hit one.
Time for me coat, those cows won't milk themselves tonight.