Agatha Christie Wiki

In the novel N or M?, Monroe is the name (probably of a local Leahampton resident) who is mentioned, although he does not appear in person. Tommy is accompanying Mr Walters and Dr Curtis on a walk from Smugglers' Rest to Sans Souci and listened in while the two men gossiped. Among the topics of discussion is the mention that Monroe (referred to as "Old Monroe") is off his game again.