Sherlock Holmes was played by Roy Marsden with the part of Dr. Watson played by John Moffatt. John Moffatt is no stranger to radio and, in fact, played the role of Holmes, Watson and Inspector Gregson on radio. He’s probably best known for his role as Hercule Poirot in the BBC’s presentation of many of Agatha Christie’s novels on radio. Roy Marsden appeared in Granada’s “The Last Vampyre” with Jeremy Brett.
Unlike most full cast adaptations, these featured mostly Dr. Watson’s narration interspersed with acted sequences. This technique is quite effective especially since it mimics how most people perceive the stories from the canon.