I know of 2 herds of these Highland cattle on Dartmoor.
One is contained within an area bordered by dry stone walls, while the other
herd roams free across the open moor.
However, even with free access they don't seem to stray far and can easily be found. 
Its been a very hot day and rather than sheltering under trees, this group of cows with calves were chewing the cud beside the road. I couldn't resist them.
They are clearly used to their celebratory status and posed beautifully while I snapped away.

P and C came over for a Bar b in the evening. You could almost believe that times are normal again