The speed limit when passing horse riders or horse-drawn vehicles is 10 mph.
When passing a horse you should always pass wide and slowly.
You can find more information in Rule 125 of the Highway Code which states:
Horse riders and horse-drawn vehicles. Be particularly careful of horse riders and horse-drawn vehicles especially when approaching, overtaking, passing or moving away. Always pass wide and slowly. When you see a horse on a road, you should slow down to a maximum of 10 mph. Be patient, do not sound your horn or rev your engine. When safe to do so, pass wide and slow, allowing at least 2 metres of space.
Feral or semi feral ponies found in areas such as the New Forest, Exmoor and Dartmoor require the same consideration as ridden horses when approaching or passing.
Horse riders are often children, so take extra care and remember riders may ride in double file when escorting a young or inexperienced horse or rider. Look out for horse riders’ and horse drivers’ signals and heed a request to slow down or stop. Take great care and treat all horses as a potential hazard; they can be unpredictable, despite the efforts of their rider/driver. Remember there are three brains at work when you pass a horse; the rider’s, the driver’s and the horse’s. Do not forget horses are flight animals and can move incredibly quickly if startled.
