I'm currently working my way through the historical/crime/espionage novels by John Lawton, featuring Frederick Troy of Scotland Yard. Very entertaining, fairly well-written, and full of well-researched historical bits large and small. The time period ranges from 1934 to the early 60s. Primary location is London, of course, but there are interesting sidetrips to other parts of Britain, Vienna, Berlin and other places I haven't read about yet. Have so far finished Blackout, Old Flames, Bluffing Mr. Churchill (Riptide in the UK), and Second Violin. A Little White Death, Flesh Wounds (Blue Rondo in the UK), and A Lily of the Field remain to be read. I'm also working on expanding Mr. Lawton's Wikipedia article - adding links to historical topics, of course.
The WWII era has been extensively mined for novel settings, but Lawton introduced some historical topics I'd never heard of. In Second Violin, which I just finished, the reader learns that Britain had internment camps before and during the war. Being from California, I'm aware of the wartime internment by the U.S. of Japanese-American residents living near the Pacific coast, but I never knew Britain did something similar to Germans, Austrians and Italians. The disturbing difference between the two counties' programs is that two-thirds of the 120,000 interned Japanese-Americans were native-born American citizens (including many children). Thus, in Second Violin, Rod Troy (Freddie's older brother) is interned, but only because he failed to become naturalized when he had the chance.