In the novel A Murder is Announced, Elinor Simmons is the mother of Patrick and Julia. Miss Blacklock hadn’t seen her since a wedding thirty years before, but Elinor had sent a photograph of Patrick as a child. She wrote to Letitia asking if Patrick and Julia could stay with her. She lives in Cannes.
She doesn’t appear in the novel, but is mentioned. Elinor is not mentioned in the various adaptations of the novel. In the 1985 BBC adaptation, Letitica Blacklock does receive a similar letter but the sender's name is not mentioned. In Murder Party, the TV film adaptation of the novel by France Télévisions, there is a parallel character of Nadine Combet.