Born in Hascombe, Surrey, the eldest of five girls, and educated by a governess at home. The artist was encouraged to draw and paint from an early age. In 1908-9 she lived with her uncle in India. Her diary from that time records an expedition over the Khyber Pass on horseback, and evening parties and dances. In 1910-11 she lived in Paris and studied at Julian's Academy, drawing from the nude and learning etching and dry-point printing from copper plates. Her major influences were Meryon, Whistler and others.

In 1911 she married John Fischer Williams and they built a house on the south coast of Cornwall where they settled from 1920-1931, spending time also in Paris and travelling widely in France, Holland, Belgium and Italy. Four daughters, three of whom were to have important international careers in law, medicine and psychiatry respectively, aside from literature, were brought up by Marjorie. She was also stepmother to Barbara, Jack's daughter by his first marriage.

She specialised in drawing and etching of church architecture. Her subject matter was the back streets, peasant scenes, flowers and countryside. From 1931 the family spent summers in Cornwall and after her husband's death in 1947 she continued to visit France in order to sketch. Lino-cut designs were also an interest, and she printed curtains and cushions. Her WWII diary is available at the Hypatia Trust, along with writings by her daughters, Jenifer Hart, Dr Mariella Fischer-Williams, and Judith Hubback. Three of her etchings were displayed in the Group Show at Falmouth in 1996, Fisherman's Workshop, Cobbler's Shop (Cornwall) and Treveague Farm.