When the detectives are introduced at the door as 'Barnaby and Jones', American viewers might find it a mildly amusing reference to a 1970s TV detective; though the reference may be entirely unintentional.
Richard Johnson plays Rex Masters in this episode. He previously played the role of James Fitzroy in episode 3.1, Death of a Stranger (1999).
Samuel West plays Jeremy Thacker in this episode. He returns in episode 19.5, Death by Persuasion (2017), in the role of James Oswood.
David Troughton plays Miles King in this episode. He previously played the role of Brian Clapper in episode 1.2, Written in Blood (1998).