She is a background character in Prisoner Cell Block H. She is the silent prisoner who is inducted alongside Susie Driscoll in (260). She has been seen previously in the halfway house run by Karen in (108) (109) and (112), where she is called "Louise". The same actress appears as one of Faye's two heavies in (342), where they are named as "Mary" and "Jill" - the other is Bev Hey, who is later called "Mary Adler", so either of them could be the real Mary. She appears in episodes almost through to the end.
She was played by actress Betty Doran.