I ended up with a copy of the audiobook, and was never fooled into thinking it was from a classic line despite the cover.
Like some other reviewers, I kept being thrown out of this story by easily researched background details — we’re told this takes place in 1930, in Suffolk. Is that West Suffolk, or East Suffolk (the two were merged only in 1974)? A character is depicted as lying around and listening to dance music on the radio, on the Light Programme. In 1930, the BBC was broadcasting as 2LO (London) and 5XX (Daventry) until March, when it transitioned into BBC National and BBC Regional, neither of which played much by way of dance music during that period — in fact, at that time the BBC was on air, during the week, from 12 noon to 4pm, and then 6pm to 11pm or midnight; Saturdays from noon to midnight. This is all available via the BBC Genome page, which includes an archive of The Radio Times
Then there’s the railway business. Even a pre-British Railways line would have been running more than a single coach on even a lowly branch line, with consists likely to include the locomotive (likely a pannier tank engine, 2-4-2), two coaches, at least one goods van, and the brake van. If we take the passenger service of the Mid-Suffolk Light Railway (absorbed eventually by the LNER) as fitting the story, then the consists would be somewhat longer than that. As for the signaling…hydraulic? Ridiculous. Honestly, signalmen would be happy to have a hydraulic assist — pulling those signal/switching levers is very hard work. Aside from rod systems, and wire, electrical systems were coming into play for certain things.
Then there’s the police.
The majority of the book is an attempt at a period whodunnit, though the writing is clean, competent, and relatively modern. Our amateur sleuth, Vicar Lucien Shaw, is a congenial fellow, quietly assisting the lumpen Inspector Ludd and his sergeant.