Francis Bacon was born at 63 Lower Baggot Street, Dublin on 28 October 1909, of English parentage. His father, a former captain in the British army, moved to Ireland to breed and train racehorses. His mother, Winifred Bacon was from the wealthy Firth family from Sheffield. The family was based in County Kildare and rented Cannycourt House, a large residence near the town of Kilcullen.
Bacon had two brothers and two sisters. For a time, Francis was sent to live with his maternal grandmother and her husband at Farmleigh, near Abbeyleix. The Bacon family subsequently lived at Straffan Lodge, near Naas in Country Kildare. They moved back to London for the duration of the First World War. When the family returned to Ireland they witnessed at first hand the political turbulence generated by the War of Independence and the Irish Civil War.