The premise and characters derive from the 1986 novel Missing Persons by David Cook (who would co-write the BBC show). ITV had already made their own feature length adaptation of the novel, but opted out of a full series, with the BBC series choosing to rewrite it's own origin pilot. The show ran for four series, while the BBC commissioned a fifth, it never came to be.
Provides examples of:
- Abuse Mistake: Once, when Hetty fell down a staircase while walking in high heels and ending up with a black eye, D.C.I. Adams asked her to pose as a victim of spousal abuse and investigate a shelter for battered women; somehow the shelter's location was revealed to a few of the women's husbands, possibly resulting in at least one death.
- Always Murder: Often averted.
- Fidelity Test: One of the B-plots involves Robert and Geoffrey, while Hetty's occupied with another case, approached by a man who wants them to set one of these up to test his girlfriend. As Robert's too old and Geoffrey's too young, they hire a third party to do so. It backfires when the girl not only falls for it, but dumps her boyfriend for the mark. Needless to say, the boyfriend isn't happy.
- Friend on the Force: D.C.I. Adams.
- Karma Houdini: Not all of the criminals face charges for their crimes, typically due to lack of evidence. They will often face other consequences, though.
- Kitchen Sink Drama: Although a more light-hearted example than the usual, given the Oop North setting and the working class characters the series could almost be described as a Kitchen Sink version of Miss Marple.
- Little Old Lady Investigates: Hetty. A somewhat more realistic example than most, in that most of Hetty's cases were fairly small-scale in nature (or at least started off that way) and matters that the police were unlikely to be interested in. She was also a registered official private investigator.
- Oop North: The series was set in Lancashire.
- Private Detective: Unlike most little old ladies who solve crimes, Hetty actually is a registered private detective.
- Reality Ensues: Into the Little Old Lady Investigates genre; Hetty is a registered private investigator who actively stays away from major cases that are the police's jurisdiction, and tends to focus on smaller-scale incidents.