"Thank you." He settles back into his own seat and adds milk and sugar to his cup. "Oh, honestly, just Nightingale is absolutely fine. My work title is Detective Inspector, or just DI, but that has no import here, and my apprentices are traditionally supposed to call me Master, but that's not the done thing any more where I'm from." Especially when one is a well-to-do older white gentleman and one's apprentice is a Black twentysomething, he doesn't add. "What would you prefer I call you?"