Arthur Joyce Lunel Cary was born in a hospital in Derry, County Londonderry in the north of Ireland in 1888. His family had been 'Planter' landlords in neighbouring Inishowen, a peninsula on the north coast of County Donegal, also in Ulster, since the early years of the Plantation of Ulster in the early seventeenth-century. However, the family had largely lost its Inishowen property on the western shores of Lough Foyle after the passage of the Irish Land Act in 1882. The family dispersed and Cary had uncles who served in the frontier US Cavalry and the Canadian North-West Mounted Police. Most of the Carys wound up in Great Britain. Arthur Cary, his father, trained as an engineer and married Charlotte Joyce, the well-to-do daughter of a Belfast banker. After his son was born in 1888, Arthur Cary moved his family to London.