Pednor Bottom, Road Ghost

The hamlet of Pednor near Chesham is reputedly haunted by a road ghost. It is said the apparition has been seen at Pednor Bottom, a valley just south of Pednor. Unfortunately key details change depending upon which version of the experiences you read. Within a short period of time the apparition was reportedly experienced twice. The witnesses were travelling along Pednor Bottom in or on a vehicle and noticed a figure in black sitting on a gate. As the vehicle approaches, the figure jumps off the gate and is hit by the vehicle. At which point it is released that the figure is not really there. Depending upon the version you read the vehicles are either cars, in which and figure is seen by all occupants or the vehicles are motorcycles. If anyone can clarify the details of these experiences I would know to hear from you.