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In page The Mystery of the Blue Train:

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The novel "also contains a number of firsts", which include "reference to the fictional village of St. Mary Mead... [later] the home of Agatha Christie's detective Miss Marple",[1] in this work, the home of the character, Katherine Grey.[citation needed] (This location also appear in "The Tuesday Night Club", published in December 1927, the first short story to feature Miss Marple.[citation needed]) Also firsts were "appearance of Poirot's valet, George" and "of the minor recurring character, Mr Goby, who would also appear in After the Funeral and Third Girl".[1]