Stanley Morgan appeared uncredited in one episode called “The Reluctant Witness” which was aired on 26th April 1966. The character is a Detective Inspector called Wallace, and delivers a couple of lines. If you have the box set, it is on Disc no. 6. The credits on the DVD set are extensive, so it's strange that Stan's speaking part was never listed. Many thanks to Bernie Peal for the tireless tracking down of this elusive episode.