The sisters' parents regularly engaged their children in intellectual and political conversation, their Anglo-Irish father Charles being a journalist, and their Scottish mother Isabella being an accomplished pianist.

Several family members disapproved of Fairfield's career choice as they felt that it was not a ladylike profession for her to enter, and believed that it would prevent her from finding a husband.

[4] Despite describing some inequality between the education males and females received at medical school, Fairfield claimed to feel no resentment, and happily chose to devote her life to the profession.

However, several years later in 1917, following the unforeseen deaths of numerous male soldiers and doctors, the Women's Army Auxiliary Corps was established, and Fairfield was appointed as their Medical Officer.

[citation needed] Fairfield also spoke at recruiting meetings; for example in Perth in September 1918 when, along with Alice Low of Queen Mary's Army Auxiliary Corps and Mrs McRae, Principal of the WRNS she addressed a "Great Rally".

[citation needed] During the spring of 1945, Fairfield is recorded as visiting Soviet prisoners of war awaiting their forcible repatriation at Newlands Corner Camp in Surrey.

[9] Prior to World War I, her chief responsibilities concerned the supervision of children's health and welfare, and the inspection of specialist schools for the mentally handicapped.

[citation needed] In 1920, she returned to the LCC, and obtained a law degree in 1923 in order to help her tackle difficult legal issues relating to public health concerns.

She joined the militant suffragette Women's Social and Political Union,[10] but left the group when it was felt that her professional position as a doctor may be threatened, and when she developed a critical stance against Pankhurst's authoritarianism.