She almost unwittingly gave away the fact that Britain's Second World War codebreakers at Bletchley Park had cracked the German codes in a 1941 novel. But MI5 need not have panicked when Major Bletchley appeared in Agatha Christie's N or M?
The Devon-born authoress was a close friend of Alfred Dilwyn "Dilly" Knox, a leading British codebreaker, so MI5 was very concerned when the character was included in the novel. Major Bletchley was an old Indian Army major they met during their investigation who claimed to know everything about what was really going on in the war.
MI5 believed his inside knowledge of the war was based on the Bletchley codebreaker's knowledge of German plans. But when she was questioned about him, Christie replied: "Bletchley? My dear, I was stuck there on my way by train from Oxford to London and took revenge by giving the name to one of my least loveable characters."