Ability over Appearance: Sharon Small was supposedly too pretty to play the plain Barbara Havers, but absolutely nailed the character in the pilot and won author Elizabeth George completely over. Her performance is to this day lauded as one of the best aspects of the series.
Fake Brit: The very Scottish Sharon Small as the very working-class English Barbara Havers.
Germans Love David Hasselhoff: Like most British detective drama, this show is incredibly popular in Denmark. This is unsurprising, as British series have always been popular in Denmark and vice versa (for instance, The Killing and Borgen).
Irony: one of Nathaniel Parker's earliest TV roles was in the first season of Poirot (the ep is The King of Clubs, if you want a look) He's the killer.
The Other Darrin: Lynley's wife Helen was played by three separate actresses: Emma Fielding in the pilot, Lesley Vickerage in series one through three (up until she separated from Lynley), and Catherine Russell in series five.
Reality Subtext: Interestingly, Parker's and Small's real-life backgrounds mirror those of their characters. Parker is the son of a knight (and former British Rail chairman), and, like Lynley, was educated at public schools (private, for you Leftpondians). Small, on the other hand, is the daughter of a working-class single mother, grew up in the Glasgow tenements and attended the local comprehensive school. Parker says that when Small came to visit him at the beginning of their time working together, she took one look at his house and immediately turned into Havers! (By the time Sharon finished drama school in 1989, Parker had already had his big break in Pieces of Cake.)