Mary Lytton Gore

In the novel Three Act Tragedy Lady Mary Lytton Gore is the widowed mother of Hermione, and a guest at Sir Charles' cocktail party. She seeks a suitable husband for her daughter, and currently faces difficult financial circumstances.

Mr Satterthwaite mentions recently having met Lady Mary, when he encounters Hercule Poirot at a party. (Dead Man's Mirror)

Lady Mary is described as a "tall thin woman, looking older than her fifty-five years". She has a "graceful figure", with sloping shoulders and soft brown eyes. Mr Satterthwaite is of the opinion that she must have been a beauty when she was young.

She had married a man named Ronald, who was well born, but had a bad reputation. Her family had not wanted her to marry him, but she believed that he would turn over a new leaf for her. However, she found out that her family had been right about him.

Ronald had gotten pneumonia and died when Hermione was three years old. Lady Mary was left very badly off. She had come to Loomouth, and taken Rose Cottage, where she lived with her daughter and one devoted maid.

Lady Mary is of the opinion that it would be safer for her daughter to marry an older man, like Sir Charles, because at that age, a man's follies and sins are already behind him. She prefers the idea of Hermione marrying Sir Charles, to that of her marrying Oliver Manders, as she says that there is something in Oliver that she does not understand, and she does not like some of his ideas.

Later, in Five Little Pigs, Lady Mary writes a letter of introduction for Poirot when he wants to call on Meredith Blake, during his investigation into the murder of Amyas Crale.

Portrayals
In Murder in Three Acts (1986), the character is played by Marian Mercer. The character name is changed to "Daisy Eastman", an American but also facing difficult financial circumstances.

In the film adaptation of Three Act Tragedy in Series 12 of ITV's Agatha Christie's Poirot drama series, the part of Lady Mary is played by Jane Asher.