She joined the LCC service in 1911 and in 1920 was sent on a mission to the West Indies- and in 1938 to Malta- to advise on how to deal with venereal diseases in women. In 1943 she was appointed to the Colonial Office committee on this subject. In 1942 she was appointed a member of the Ministry of Health's Advisory Committee on the welfare of mothers and young children. Earlier activities included the preparation of a report on women's lodging houses in 1927. Later that year she went to America, under the auspices of the Commonwealth Fund of New York, to study child guidance.
In WWI she became a medical area controller attached to the Women's Army Auxilliary Corps. Later she served with the RAF as inspector of Medical Services, Women's Royal Airforce, with the rank of Honorary Lieutenant Colonel. For these services she was created CBE in 1919.
In WWII she again joined the RAMC and was Chief Medical Officer of the ATS. She was retired in March 1942, having reached the age limit.
In her early years she was an active supporter of the Women's Suffrage Movement and a member of the Fabian Society. In 1930-32 she was president of the London Association of the Medical Women's Federation. She was called to the Bar by the Middle Temple and for many years regularly attended the meetings of the Medico-Legal Society of London, of which she was a vice-president. She was also co-editor of the Medico-Legal and Criminological Review.
She was also an ardent and influential member of the Catholic Church. This is borne out by her documented presence in this collection on a number of committees of Catholic welfare and special interest groups."@en , "Provenance of the material is unknown."@en ; rico:identifier "WL536a" ; rico:recordResourceExtent "c183 frames"@en ; rico:recordResourceStructure "The papers are not arranged in any particular order."@en ; rico:scopeAndContent "This collection of correspondence and personal papers of Letitia Fairfield, a prominent Catholic doctor and lawyer, deal in the main with subject of compulsory sterilisation, in particular in relation to the Nazi eugenics policy; and to the views of the Catholic Church on the subject."@en ; rico:title "Fairfield Documents: Documents re sterilisation in the Third Reich"@en .