Jason was cast in the role of Lance Corporal Jones in the Jimmy Perry and David Croft BBC comedy "Dad's Army". Croft had been very impressed with the actor and knew that he had the talent to play a man much older than his real age. However, Bill Cotton overruled him, casting Clive Dunn. Jason appeared in the BBC comedy series "Hugh and I", which starred Hugh Lloyd and Terry Scott as two friends who lived together in South London. He appeared in "Randall and Hopkirk (Deceased)" ("That's How Murder Snowballs", 1969) as Abel, a framed performer in a major London theatre.