He was the second son of Sir Simon Bradstreet, 1st Baronet of Kilmainham, Dublin and his wife and first cousin Ellen Bradstreet, daughter of Samuel Bradstreet of Gowran, County Kilkenny and Elizabeth Agar. [1] In 1773, Samuel succeeded his older brother Simon as third baronet.[2] He was educated at Trinity College, Dublin and was then called to the Bar by the Middle Temple in 1758, becoming King's Counsel in 1767[5]