Why do sheep always face the same way?

It was almost a failure to post today. I have been at the National Trust property of Thompson’s Rigg near Dalby building leaky dams and sheep gates across Crosscliffe Beck. Sheep gates to prevent sheep from passing under the new fence where it crosses the beck and leaky dams to slow down the water flow in times of high rainfall thereby helping prevent flooding further downstream. So engrossing was the task, there was no time for photography.
But I had forgotten that walking the dog this morning I had noticed sheep, Border Leicesters I think, nonchalantly grazing away all facing the same direction.

I liked the uniformity of the sheep with their heads and shoulders bathed in the morning sun. But why? It’s only a small field so it’s not as though they are purposely walking in that direction. I would have thought that sheep would have evolved to graze fairly randomly so that a predator is more likely be spotted early in spite of their excellent 270º peripheral vision. However, there is recent research using satellite photos that claim sheep and other herding animals align themselves north to south. Now I know it is not easy to judge accurately but I would guess these sheep are facing north-east so I am not convinced. It is also said that sheep tend to stand with their backs to the wind when it is cold. It was autumnal this morning but hardly a breath of wind.