SEPTEMBER: The Third Floor Flat
No references. Poirot has a cold. Probably early autumn. The song they are singing in the stair case, "Life Is Just a Bowl of Cherries", was released in early 1931, so I suggest an autumn 1931 placement of the episode. Also, the marriage certificate is dated in 1930 (as Poirot points out). Of course, the marriage might have been much longer than a year, but for the sake of a fairly even distribution of episode along the timeline, I think we can safely place the episode here, especially since it is not specified how much time is supposed to have passed between now and the marriage.