Powell was born in Westminster, England, to Philip Powell and Maud (née Wells-Dymoke). His father was an officer in the Welsh Regiment. His mother came from a wealthy family in Lincolnshire. Powell's early childhood was spent in a flat in Kensington. It overlooked the Gardens where he often played. In 1913, the family moved to Aldershot and into Stonehurst. Stonehurst was a large bungalow on top of a hill.