Muriel and her identical twin sister Marini first studied music at the University of Auckland before training at Auckland Hospital to become registered nurses in 1928. During the Second World War they joined the New Zealand Army Nursing Service in 1940. Muriel left New Zealand in 1941 for Cairo to work in a tent hospital before spending nearly a year in a tent casualty clearing station in Italy, only 12 miles from the front line. Both sisters received the Royal Red Cross medal for their war service and had notable nursing careers in Auckland after the war. In 1966 Muriel became one of the few New Zealanders to receive the Florence Nightingale Medal for outstanding services to nursing.After the war she undertook further training at the Royal College of Nursing and when she returned to New Zealand in 1946 she became Supervising Tutor for the Auckland Hospital Board. Both sisters retired in 1955.

Muriel Jackson is quoted in the Auckland War Memorial Museum exhibition 'Scars on the Heart', 'The facilities were all under canvas. The winter was bitterly cold. It rained most of the time and we were literally bogged down. We never got out of our gumboots for four months and as the army moved north so did we.' AWMM