Freeman Willis Crofts
The most marked effect of The Hog's Back Mystery was to make me realize what a good writer Agatha Christie was.
That is not a conventional literary judgment, by the way. Most critics sneer at Christie for "two-dimensional characters", for a "flat" prose style, for lack of psychological depth, for--a cardinal sin, this--being Just Not Literary. A standard comment is that a Christie novel is nothing but a puzzle, a thought exercise perfunctorily wrapped up in a novel-like package.
These critics--and they are many, including the appalling Edmund Wilson--have clearly never read a mystery that really is a pure puzzle. The Hog's Back Mystery is such a one. As a puzzle, it's quite accomplished. As writing, it's ... well, Crofts was trained as an engineer; he seems to have approached the writing as one of those pointless-but-necessary things that clients require to bridge the gaps between the really interesting bits, such as finite-element analysis or object-functional decomposition diagrams or (in this case) elaborate timetables.
The result is, at best, awkward. Christie, for example, knew how to convey a clue so subtly that the reader never notices. Crofts does things like writing an entire scene in descriptive text--except for three lines of stilted dialogue, which needless to say are A Vital Clue. More generally, he uses narration when he should use speech; he uses speech when he should use narration; he's constantly telling us what the characters feel, rather than showing us; the characters themselves are not even two-dimensional; and there's not a trace either of descriptive writing or of humor. The detective, Inspector French, is positively featureless; I couldn't tell you anything about what he looks like, or how he approaches a case, or his personality.
And then there are lines like this:
Once again French registered a vow that he would not rest till the devil who was guilty of this ghastly crime had paid for it on the scaffold.Ouch.
Agatha Christie gets no critical love because she used her gifts in ways that are conventionally deemed worthless. It doesn't follow from that that she wasn't gifted, or indeed that her choices truly are worthless. (Also, she was perfectly capable of going outside her usual lines. Think of And Then There Were None.) Freeman Willis Crofts was a careful constructionist and not much else. The difference is striking.
Dorothy Sayers's The Five Red Herrings is clearly Croft-esque, but Sayers was a vastly superior writer (and had a vastly superior central character to work with). If you're looking for an unjustly-overlooked master from the Golden Age of Detective Fiction, check out the witty and devilishly clever Cyril Hare.