In preparation for the role, David Suchet read every single book and short story Poirot appears in: "I had my file on one side of me and a pile of stories on the other side and day after day, week after week, I ploughed through most of Agatha Christie's novels about Hercule Poirot and wrote down characteristics until I had a file full of documentation of the character. And then it was my business not only to know what he was like, but to gradually become him."
As of 2013, the entire Poirot canon written by Agatha Christie has been filmed for this series, with The Lemesurier Inheritance incorporated into Labours of Hercules, and Suchet giving a reading of the only stage play, Black Coffee for The Agatha Christie Theatre Company.
During the filming of the first series, David Suchet almost left the production during an argument with a director, insisting that Poirot's mannerisms (specifically, putting a handkerchief down before sitting on a park bench) be featured.
While at least some of the stories take place in 1935 (in Season 1, Episode 2, the date of Guy Fawkes Day is given as November 5, 1935), Florin Court in Charterhouse Square, the building that serves as the location of Poirot's flat, wasn't built until 1936.