It's not common throughout the country, but the roads in question are within the New Forest where there are a large number of ponies and other animals roaming free ..

https://en.wikipedia.org/wiki/New_Forest#Ponies,_cattle,_pig...

It's also worth noting that while wild, New Forest animals are very comfortable around people and cars, to the degree that they're often wandering around in village centres, standing in the middle of the road etc.

If you go camping there, you should expect ponies to wander in to your campsite, especially if you leave food out. I've had one poking its head in to our tent before.

They basically have total right of way, and they know it.

There's a stable right next to the intersection https://www.google.co.uk/maps/@50.8609001,-1.4574099,254a,35...