Hercule Poirot of Police of Brussels, until "the Great War" (World War I) forced him to leave for England. (In "The Mysterious Affair at Styles" Poirot had retired at age 55 in 1905) I had called in at my friend Poirot's rooms to find him sadly overworked. So much had he become the rage that every rich woman who had mislaid a bracelet or lost a pet kitten rushed to secure the services of the great Hercule Poirot. During World War I, Poirot left Belgium for England as a refugee (although he returned a few times). On 16 July 1916 he again
Hercule Poirot of Roger Ackroyd". It has been said that the twelve cases related in "The Labours of Hercules" (1947) must refer to a different retirement, but the fact that Poirot specifically says that he intends to grow marrows indicates that these stories also take place before "Roger Ackroyd", and presumably Poirot closed his agency once he had completed them. There is specific mention in "The Capture of Cerberus" of the twenty-year gap between Poirot's previous meeting with Countess Rossakoff and this one. If the "Labours" precede the events in "Roger Ackroyd", then the Ackroyd case must have taken place around twenty