Who is Mary Anne from All About Love and what is their importance?

Mary Anne is the friend who is responsible for Phyllida's presence at the crime scene. Mary Anne is in love with her boyfriend, Robert, who she has been seeing for a long time against the wishes of her father. Robert does not have the means to provide for Mary Anne should they marry. This is the reason that her father has forbidden her to see him. Her father's disapproval doesn't stop the star-crossed lovers. They simply meet in secret and bide their time until Robert can complete his registration.