After completing her first degree in English literature Mary trained as a nurse at the Middlesex Hospital in London. She specialised in oncology nursing early in her career, and completed an oncology nursing certificate at Sheffield's Weston Park Hospital.
She then moved to Oxford where she worked first as a research sister with the Imperial Cancer Research Fund, and then as nurse manager of the regional bone marrow transplant unit. During this time she undertook a research Masters degree at King's College London. This led to her PhD research, a grounded theory study of nurses' personal involvement in relationships with cancer patients, for which she was awarded a 3-year studentship from the Department of Health.
Having gained her PhD in 2000 Mary returned to clinical practice as a Macmillan Breast Care Specialist Nurse, first at Furness General Hospital and then at Royal Lancaster Infirmary. She undertook a Macmillan Management Fellowship, and was then seconded to Cumbria and Lancashire Strategic Health Authority, where as Assistant Director of Nursing she had responsibility for leading on End of Life Care. She also managed the Preferred Place of Care project for Lancashire and South Cumbria Cancer Network.
In February 2007 Mary took up her current post as a research associate at Lancaster University and joined the growing team in the International Observatory on End of Life Care. Her role is to support Professor Sheila Payne in developing new research into hospice care.