Sarah Campion was born Mary Rose Coulton in Eastbourne, England. She was brought up in a village near Cambridge University, where her father, G.G. (George Gordon) Coulton, a medieval historian, was a lecturer. She worked as a teacher in England, Canada, and Scotland before traveling to Germany to teach English to German Jews. In 1937, she was expelled from Germany by the Nazi regime. She then travelled through Canada, the USA, South Africa, New Zealand and Australia, working as a cook. In 1939, she spent six months staying on the Atherton Tablelands in northern Queensland, which inspired her six Australian novels, including the trilogy Mo Burdekin (1941), Bonanza (1942), and The Pommy Cow (1944). They were published under the pseudonym Sarah Campion, derived from the names of her grandmother and 16th-century poet Thomas Campion. She returned to England at the outbreak of World War II and worked as an editor, reviewer, and broadcaster. In 1949, she married Antony Alpers, a New Zealand writer, and later emigrated to New Zealand with him and their son Philip. She became well-known in New Zealand as a writer, commentator, radio broadcaster, and political activist.