Edith was a non-canonical character who was created for the film adaptation of Four and Twenty Blackbirds in Season 1 of ITV's Agatha Christie's Poirot. It is not clear which character in the episode is Edith. However there is a scene where Irene Mullen is with another woman, discussing why Henry Gascoigne's milk is piling up uncollected outside his door. The other woman, obviously a neighbour, agrees that everything has been very quiet in his house. The two women finally break into his house and find his body. This woman with Irene Mullen has many lines and could be Edith.
Edith was played in the film by Su Elliot. This character does not exist in the original story.