Katherine Elsworth

In the novel They do it with Mirrors, Katherine Elsworth is the birth mother of Pippa San Severiano, and the biological grandmother of Gina Hudd. Katherine was hanged for administering arsenic to her husband. According to Miss Marple, it was rather "a celebrated case".

Portrayals
In the 1985 adaptation of the novel, her first name was changed to Frances. Similar to the novel, she poisoned her husband with arsenic. In this adaptation, it is stated that she was hanged in 1943.

In the 2009 adaptation of the novel, the character of Pippa is not present. Katherine Elsworth is the birth mother of Gina Hudd, who is Carrie Louise's adopted daughter in this adaptation, not her granddaughter. In this adaptation, Katherine Elsworth was found guilty on three counts of poisoning by arsenic, and was hanged on 4th September, 1927.