A correspondent known to me as Gunnar asks the following question. Perhaps those of you who have read more early detection fiction than I can tell us more:

    “Tony Baer’s recent review of A. A. Milne’s Red House Mystery (1922) got me thinking of the origins and early history of the country house mystery. I suppose you can trace its early prototypes back to Wilkie Collins, but later Sherlock is mainly metropolitan – and while Baskervilles, Valley of Fear and some of the short stories do feature country houses or castles, they’re not really country house mysteries in the true sense (with a closed circle of suspects and all that).

    “The first proper instance I can think of is The Mystery of the Yellow Room (1907) followed perhaps by Trent’s Last Case (1913) and then of course Styles (1920). Are there other early examples that predate Christie’s debut?”