Alexander Simpson

In the short story The Girdle of Hyppolita, Alexander Simpson is an art dealer as well as a friend of Hercule Poirot. He owned "Simpson's Galleries". When a painting by Rubens was stolen from his gallery, he asked Poirot to help. He told Poirot that he thought he knew who was behind the theft: a certain millionaire who lived in France. In his opinion, going through the official channels of investigation would take too long. The police would have to tread carefully because the suspect was a rich man, and even so, they may not succeed.

Poirot was not particularly interested in the case but took it up to oblige his friend and also because the subject of the painting matched one of the cases he was trying to find for his portfolio of the "Twelve Labours of Heracles".