By Christopher Pittard, Senior Lecturer in English Literature, University of Portsmouth - A hundred years ago, Agatha Christie introduced British readers to a small man with an impeccably maintained mustache who, with the help of his “little grey cells””, was very good at solving crimes. That man, of course, was Hercule Poirot, who made his debut in Christie’s first novel, The Mysterious Affair at Styles, in 1921.