Men of subtle craft by Roy Lewis (1987) is about a council planner turned amateur historian called Arthur Landon who is asked to help out in a rather obscure academic argument over a medieval mason. While Landon is travelling around the rural north on both council and historical business, he becomes involved in a bitter local dispute over inheritance and broken marriages. This eventually results in a murder with a rather unusual MO, though the murder does not occur until quite late in the story.
The story takes a while to get going though does help build the characters nicely. The historical sub-plot can be a bit impenetrable at times and doesn't really have anything to do with the crime but does provide a setting and a few red herrings. The final act ups the pace considerably. A fine read.