The series is set in 1952, and a street scene shows a Routemaster bus. The first prototype of this bus was not presented until 1954. Interior scenes from a Routemaster are shown in all three episodes as well.
Timothy's (Susan's husband's) car is a Morris Oxford. However the fluted bonnet (hood) and the two-tone paintwork belong to a Mark III model that was first released in 1956, whereas the episode is set in 1952 - nine years after the "1943" caption in the opening titles of Cracking a Killer's Code: Part 1 (2012).