Murder While You Work by Susan Scarlett, for Dean Street December

Lively and attractive Judy Rest has given up nursing but is still determined to do her bit for the war in this WWII mystery by Susan Scarlett, aka Noel Streatfeild. Judy is heading to the country to work at a munitions factory, and has a meet cute on the train when a studious-looking young man obligingly crawls about on the floor retrieving the lipstick she dropped.