Rankin was born on 28 July 1908 in
South Brisbane, Queensland. She was the older of two daughters born to Annabelle Davidson Rankin (née Thomson) and
Colin Dunlop Wilson Rankin. Her father, born in Scotland, was a sugar grower and
Boer War veteran who served in the
Queensland Legislative Assembly (1905–1918). Rankin grew up on her father's sugarcane farm on the
Isis River near the small town of
Childers. In 1919, her father replaced his deceased brother as managing director of Queensland Collieries Company, necessitating a move to
Howard. Rankin attended the local state schools in Childers and Howard before completing her education as a boarder at the
Glennie Memorial School in
Toowoomba. As an unmarried woman from a wealthy family, Rankin was not expected to enter the workforce. She involved herself in various community organisations, teaching
Sunday school and founding a local unit of the
Girl Guides. She was encouraged by her father to travel overseas, visiting China and Japan soon after leaving school. She visited Europe in 1936, working in the slums of London and with refugees from the
Spanish Civil War; while in
Gibraltar she witnessed the bombing of
La Línea de la Concepción. After her father's death in 1940, Rankin began working as a clerk for the Union Trustee Company of Australia. She was the commandant of a Brisbane-based
Voluntary Aid Detachment during the war. She was also state secretary of the Girl Guides in 1942 and assistant state commissioner of the
Young Women's Christian Association (YWCA) the following year. She was responsible for the organisation's work around the welfare of servicewomen, in which capacity she travelled to military bases in North Queensland. In 1946, she was offered a position in Greece with the
United Nations Relief and Rehabilitation Administration, but declined in order to enter politics in Australia. ==Politics==