Joe Carstairs was born in London in 1900, the daughter of a Scottish colonel and an American heiress. She was educated in Connecticut and returned to Europe in 1916, to drive ambulances for the Women's Legion in France. She deserted her husband at the church door (marriage having been a prerequisite of her coming into her $4 million inheritance) and settled in England, where she took up motor-boat racing, winning many trophies, and established a boatyard at Cowes.