She was the youngest daughter of Alexander Leslie, 5th Earl of Leven and the mother of James Walker, a Rear admiral in the British Royal Navy.
Her works included discussions of philosophy, education and art.
Advanced in thinking for the time period, she was a strong advocate of education for women.
Her most successful novel, Munster Village (1778), centres on a utopian garden city populated with fallen women and females escaping disastrous marriages.
Jane Austen may have been influenced by her writings, taking the same names as some of Lady Mary's characters.