Willy Bowman makes a brief, non speaking, uncredited cameo appearance as dead villain "Joseph Castle" in a flashback sequence. The following year he would make another, brief, one scene, non-speaking appearance as "Billy Moffat" rival to "Harry Grout" in the Porridge, series two episode, The Harder They Fall.
One of the tower blocks visible from the window of Stephen Castle's office is Grenfell Tower, scene of the tragic fire in 2017.
This edition was the most-watched programme on television that week, topping the charts with 9.4 million under the JICTAR Ratings System.
Hywel Bennett (Steven Castle) previously appeared with John Thaw in Night Watch (1964) (Bennett's first TV appearance). He also previously appeared with Dennis Waterman in Alice's Adventures in Wonderland (1972)
Peter Brayham (Johnno Smith) previously appeared in the pilot Regan (1974) as Edward Grenfell-uncredited, Ringer (1975) as Crook-uncredited and in Selected Target (1976) as Flying Squad Officer-uncredited. He was also stunt arranger in 19 episodes and both films, stunt coordinator in Thou Shalt Not Kill! (1975) and stunt performer in Ringer (1975)