[2] In 1924 she qualified for a diploma from the South Australian branch of the Australasian Massage Association and opened a private physiotherapy practice which she maintained until a few weeks before her death.
For twenty years she worked part-time at the Adelaide Children's Hospital, where she encountered many cases of infantile anterior poliomyelitis, an acute infectious viral disease affecting the brain and spinal cord, causing weakness, paralysis, and wasting of muscle, for which the classic treatment was bed rest and immobilization of affected limbs.
Between 1944 and 1964 Finnis gave lectures on physiotherapy at the University of Adelaide and supervised practical classes in paediatrics at the Children's Hospital.
[2] Finnis was a knowledgeable music lover, having studied piano at an advanced level,[5] and was from 1932 a member of Adelaide's Tatlers Club, a literary society.
She was a regular church-goer, an adherent of the Church of England and, with her husband, a foundation member of the Friends of St Peter's Cathedral (founded 1932), and active in that group until 1954.