I just finished
A Test of Wills (Inspector Ian Rutledge Mysteries) by Charles Todd - the author is actually a mother-son writing team, and all of their books are set in post-WWI England. It took me a while to get to the Inspector Rutledge series, I'm not sure why (they also have a newer series featuring a nurse).
Rutledge has just gone back to work after being hospitalized for shell shock, and he continues to hear the voice of a dead soldier, even though he knows it's not real; and he's recently been dumped by his fiancee. He's groping his way towards his new, postwar self and trying to find again the sense of intuition that made him a good detective. The case he's assigned (by a jealous colleague) is complicated by having a war hero for one of the suspects, and a badly shell-shocked soldier for one of the important witnesses.
I enjoyed the variety of interesting female characters, and the complexity of the mystery, though the solution to the mystery itself was a bit more wacky than I had expected, and definitely unexpected, at least to me. I plan to read more of this series.
I read Jacqueline Winspear's Maisie Dobbs, also set in post-WWI England, when it came out, but though I thought it was excellent, I didn't feel the need to read any more in the series as it grew. The first one depressed me and left me depressed, but I don't know if all of them would. Maybe I'll give them another shot one day.
Anne Perry also has a WWI mystery series, but the first one, No Graves As Yet, turned me off in some way I can't explain (voice? tone? character?), and I didn't get very far. I strongly doubt I'll go back to that series.
Are there any other mystery series set in this period I should know about?