In this first episode, Inspector Frost stops smoking cigarettes. In real life, actor David Jason had recently quit smoking.
This pilot episode is based on the first Frost novel "Frost at Christmas", which was written in 1984 (and set at Christmas), and generally follows the book's plot in terms of the two main cases (Tracey Uphill's disappearance and the skeleton's discovery) aside from a major change to the ending of both. The novel's minor subplots are dropped for the episode, which included ongoing vandalism to the bank which tied-in to the blackmail of PC Stringer by a local crime figure over gambling debts. Frost's wife had also already passed away the year prior and he was seeing Shirley (who was not a nurse) on a casual basis, but this was changed in the episode to set up Shirley as an ongoing love interest for Frost as the series progressed. Frost is more or less portrayed the same in the episode as the novel, albeit much more sympathetic to victims of crime and nearly completely inoffensive, compared to the crude and sleazy literary version who constantly leers at attractive young women and plays frequent practical jokes on colleagues and witnesses. Barnard is likewise toned down in the episode compared to the book, in which, like Mullett, he despises Frost's policing methods despite his popularity at the station. Frost's relationship with DCI Allen (who is actually still a DI in the novel, awaiting promotion) has perhaps the biggest contrast; both men hate each other in the book but this was changed to a much more natural, respectful association for the series with only minor tension.
The first appearance of Matt Bardock as D.C Clive Barnard in future episodes he would be promoted to D.S Barnard
The first appearance of Caroline Harker as WPC Hazel Wallace in future episodes she would be promoted to D.S Wallace.
This episode introduces the original characters of Frost, DC Barnard, Mullett, DCI Allen (DI in the novel), DS Toolan (DS Martin in the novel), Sgt. Wells, Sgt. Johnson, Sgt. Hanlon (DS in the novel), PC Simms, PC Jordan, WPC Hazel Wallace (Hazel Page in the novel), PC Stringer, newspaper editor Sandy Longford (Sandy Lane in the novel), Shirley, pathologist Simpkins (Drysdale in the novel), his assistant Miss Grey, and Dr McKenzie, the police duty doctor. No other detective constable appeared in the novel, so DC Mark Howard was created for the series as an additional regular CID officer and based on DC Burton, who was introduced in the second novel "A Touch of Frost". The third station sergeant in the novel, Tom Henderson, was dropped and DS Hanlon, who had a much more significant role, was turned into the third uniformed sergeant for the series instead of having a second regular detective sergeant with George Toolan. Of the non-police guest characters, most are reworked to varying degrees, particularly Annie the cat lady, who was called Martha Wendle in the novel and lived alone in the woods with her cats and practiced clairvoyance, much to Frost's derision. The Uphills and Powells are generally the same, although Mrs Powell is not ill in the novel.