Background
He was the fifth and youngest son of Richard Southwell and his wife Lady Elizabeth O"Brien, daughter of Murrough O"Brien, 1st Earl of Inchiquin.
He was the fifth and youngest son of Richard Southwell and his wife Lady Elizabeth O"Brien, daughter of Murrough O"Brien, 1st Earl of Inchiquin.
Southwell was High Sheriff of County Limerick in 1707. He was elected to the Irish House of Commons for Limerick County in 1727, representing the constituency until his death two years later. Southwell married Agnes Rose, daughter of George Rose, and by her he had an only son.