Her father was a landowner from Litchfield, Connecticut, and her mother was the daughter of the banker William B. Coster.

In 1948, Mathilda married Clemens Heller, a professor of human sciences at the University of Paris.

They began a relationship shortly after meeting[1] and were married in 1963 at the Registry Office in Horsham, West Sussex.

In her later years, she wrote a novel called Orian — A Philosophical Journey, inspired by the death of her youngest son.

She also had a keen interest in photography, and once held an exhibition of her work at the Demarco Gallery in Edinburgh.