Who is Mrs. Horsefall from A Town Like Alice and what is their importance?

Mrs. Horsefall, a former teacher, assumes the role of group's first leader. Her ten-year-old son, John, is with her in captivity. Over the course of the story, Horsefall protests the lack of beds, is physically abused by Captain Yoniata, and negotiates realistic walking schedules with the groups captors. Mrs. Horsefall dies in 1942 from complications of Malaria.