I think they have been confirmed to be living down here in Devon. Exmoor has had literally dozens of sightings and farm animals killed over the years. They even sent the army in to shoot them a couple decades ago. As has been said above they are just survivor offspring of animals released onto the moors in the 70's after animal licensing laws came into effect. I doubt there are very many, but I'm pretty certain they are they out there, sadly the only cryptids that are.