Jason appeared in variety shows as the supporting act of Dick Emery and his performances caught the attention of Ronnie Barker. Jason was recruited to appear in "Hark at Barker" (LWT, 1969), starring opposite Barker's Lord Rustless, as Dithers, the 100-year old gardener. There was also a sequel, "His Lordship Entertains" (1972) for the BBC. Jason played idealistic employee Granville in the first programme of the comedy anthology "Seven of One" (1973), called "Open All Hours" (BBC) and starring Barker as the curmudgeonly proprietor of a corner shop.