Mr Thompson said, in his view, Hugo had driven into a bend on the road too fast, causing the vehicle to come off the road.
He said he calculated the maximum theoretical speed around the bend was 38mph.
But he added: “Having driven the bend myself the fastest speed I felt comfortable negotiating the bend was 26mph.”
He said the Ford Fiesta had entered that bend at a speed that was in excess of the limit to negotiate it, even though that may well have been below the road’s 60mph limit.
Mr Thompson said the actions of Hugo Morris needed to be considered in the accident.
While it had been raining heavily, with leaf cover on the road, the investigator said he did not consider weather conditions played a role in the collision.
But he said in his view, the crash “was avoidable”.
