Which TV adaptation featured one actor playing two separate parts throughout its 37 episodes?
Brian Poyser:  His appearances include the musical "Poppy", the BBC Television Shakespeare (including a senator in "Coriolanus", and Gower in "Henry IV Part 1" and "Henry V"), the series "Sex, Chips & Rock n' Roll", an episode of "Agatha Christie's Poirot", and as the recurring character the Revd Aubrey Stewart in two episodes of "Foyle's War" ("The French Drop" and "Plan of Attack"). BBC Television Shakespeare:  Transmitted in the UK from 3 December 1978 to 27 April 1985, the series spanned seven seasons and thirty-seven episodes.
BBC Television Shakespeare