In Look - (Stop Me If You've Heard This One) But There Were These Two Fellers... (1968), Robert James' character name was also "Merlin".
In the novelisation of this episode, Bodie confronts Geraldine Mather in the courtroom after they bring in the badly-beaten Parker and blames her for his condition. One wonders if this scene was actually shot and then cut.
This episode was written as a reaction to complaints about the violence depicted in the series.
The episode was originally called An Inquiry into Violence, but LWT thought it was too contentious.
Michael Billington later reminisced about the episode - "About the time of doing [this episode of] The Professionals (1977) I had just come back from Paris where I had been doing some tests at the time of Moonraker (1979)...I can remember that The Professionals was a good set, very fast and professional. I can recall getting on pretty well with Lewis Collins who had a good sense of humour! I can recall that I plucked my eyebrows completely off to play the role of the ex-boxer Coogan because it made me look a bit insane! It was a bit of a nuisance afterwards because it took YEARS for them to grow back completely. I also had a difference of opinion with (director) Peter Medak over the way I played the courtroom scene. To show Coogan's deviousness I played his as though he was innocent and sincere! Peter wanted me to play him callous and hard! Maybe he was right! I think it came out somewhere in the middle!"