Poirot, Miss Oliver and Supt. Wheeler walk around the memorial discussing the case. Later on Poirot and Colonel Hughes do the same in episode 10x02 "Cards on the Table".
Source: IMDb
From episode 8x12 "My Mother, My Chaperone/The Present/The Death and Life of Sir Albert Demerest/Welcome Aboard: Part 2".
Source: IMDb
From episode 6x07.
Source: IMDb
From episode 1x01.
Source: IMDb
Source: IMDb
Source: IMDb
From episode 1x03 "Having It All".
Source: IMDb
Source: IMDb
Source: IMDb