Dr Clay supplied his first-hand account of the story to L V Grinsell for his book 'The Archaeology of Wessex' (p57).
'During the winter of 1927/8 when Dr R C C Clay was excavating the Pokesdown urnfield, he met with the following experience. One night he was returning from Pokesdown to his home at Fovant and proceeding in his car along the road from Cranborne to Handley, when about 150 yards past Squirrel's Corner he saw a horseman on the downs to the north-east, travelling in the same direction as himself.
"Thinking he was from the Training Stables at Nine Yews, I took very little notice of him at first. Suddenly he turned his horse's head and galloped as if to reach the road ahead, before my car arrived there. I was so interested that I changed gear to slow my car's speed in order that we should meet, and I should be able to find out why he had taken this sudden action. Before I had drawn level with him, he turned his horse's head again to the north, and galloped along parallel to me about 50 yards from the road. I could see now see that he was no ordinary horseman, for he had bare legs, and wore a long, loose coat. The horse had a long mane and tail, but I could see no bridle or stirrups. The rider's face was turned towards me, but I could not see his features. He seemed to be threatening me with some implement which he waved in his right hand above his head. I tried hard to identify the weapon, for I suddenly realised that he was a prehistoric man; but I failed. It seemed to be on a two foot shaft. After travelling parallel to my car for about 100 yards, the rider and horse suddenly vanished. I noted the spot, and the next day found at the spot a low round barrow."
'A few years later, the late Alexander Keiller reported to Dr Clay that two girls, returning from Cranborne to Handley from a dance, had complained to the policeman at Handley that they had been followed and frightened by a man on horseback. Within the last thirty years [since 1958] there have been other reports, from shepherds and others, of apparitions having been seen in the vicinity of Bottlebush Down.'