Thomas had emigrated to Ireland from Devon in the late seventeenth century and acquired the Morgans estate.
Henry was educated at Magdalen Hall, Oxford, entered the Inner Temple in 1696 and was called to the Irish Bar in 1701.
Given his record of opposition, his appointment as a justice of the Court of King's Bench (Ireland) in 1734 caused some surprise, although he had been counsel to the Revenue Commissioners since 1722.
He probably owed the first appointment to his friendship with William Conolly, the long-serving Speaker of the Commons.
Sarah married as her first husband her cousin John Southwell of Enniscourt, County Limerick, only son of Richard Southwell MP and Agnes Rose, daughter of Henry's brother George, and had a daughter Agnes Elizabeth, who married John Wandesford, 1st Earl Wandesford.