Millie (Camilla) is an independent-minded single woman who vows never to be ordinary. She and Susan lose touch after the war, when Susan decides to pursue a more conventional lifestyle. Millie travels the world and seeks adventure after the war, but eventually returns to London when she runs out of money. Millie makes the decision to bring Lucy and Jean into the investigation in order to help, and quits her job at a diner when she is sexually harassed. While she is bisexual, you only find out in the Bletchely Circle spin-off.