Fact 95: Did MI5 ever investigate Agatha Christie for knowing about top-secret government information?

Fact 95: Did MI5 ever investigate Agatha Christie of knowing about top-secret government information?

Surprisingly yes, one of the greatest detective writers of all time was questioned about her knowledge of code breaking because one of the names of her characters coincidentally had a link to an MI5's secret code-breaking at BletchleyPark. Agatha Christie had a conversation with an MI5 agent\code breaker Dilly Knox who happened to be one of her friends who worked at Bletchley Park all about her knowledge about code breaking because of what was happening at Bletchley Park.

He basically asked her where did the name Major Bletchley (the character) had come from Agatha Christie then told him all about how she was actually stuck on a train near Bletchley (Agatha Christie was going from Oxford to London) and so as her revenge for the train delay she named her "least loveable character" after the place. 

I would imagine that MI5 breathed a well-deserved sigh of relief as they thought the knowledge of the code-breaking at Bletchley Park might have got out.

 I did a bit of research on book was called N or M, (I read a summary) and is about (you guessed it) WW2 code breakers and is described by many as a feel-good spy thriller, so I personally can understand MI5's concerns about Agatha Christie knowledge.