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Whilst Hathaway is on leave, DS Innocent assigns DC Gray to assist Lewis. She tells Robbie that no one volunteered to work with him except for Gray. In part two, at the end of that episode, Liam (whose father had died) is speaking to DC Gray. Gray tells young Liam to stay composed as a lot will now be happening with police and coroner involvement and he'll need support as Gray's father died when he was young too. Liam asked him if anyone helped him during during his bad period, Gray says, "A copper - A Geordie", referring to Lewis. That is why he volunteered to be Lewis's sidekick.
The names of crew members Pauline Harlow (script supervisor) and Steve Fish (sound maintenance) appear on the white board of the undertaker as the names of corpses to be cremated.
The title of this episode, "The Ramblin' Boy," refers to the 1964 Tom Paxton song. The father and son are singing the song in the opening scene. And--near the end of the episode--the son, sitting on a bench, is listening to it over his headphones as Lewis approaches him
This episode happens to feature Taron Egerton, speaking and singing with his actual Welsh accent, when he was a relatively unknown actor, in a relatively minor role, hence his name isn't in the opening title credits. He would later become very well known for playing Eggsy in the Kingsman film series, and Elton John in the biopic Rocketman.
Peter Davison is also known as the 5th Doctor, in the Doctor Who franchise and Father-in-law to David Tennant, the 10th Doctor. David Tennant co-starred in Doctor Who with Billie Piper, and attended her wedding to Laurence Fox, DS James Hathaway. Note: the couple has since split.
Referenced in this episode was a BBC police procedural television series, "Dixon of Dock Green" (1955 to 1976). The central character, George Dixon, was a mature and sympathetic police constable.