The Clock Strikes Twelve
by Patricia Wentworth (J. B. Lippincott, 1944)
audiobook read by Diana Bishop (Isis, 2010)
Wentworth cheats a little by employing an expurgated omniscient narrative to deflect attention. The ever-coughing Miss Silver is like a cuddly Miss Marple, and has the distinction of solving the murder as she goes, rather than keeping mum for a big reveal.