The third son of Arthur Stuart, 7th Earl Castle Stewart, and his wife Eleanor May, daughter of Solomon Guggenheim and Irene Rothschild, he became his father's heir apparent after the death of his two elder brothers during the Second World War.
He was also a trustee of The Christian Community in the United Kingdom from 1973 to 2001; a fellow of the Chartered Management Institute;[5] and chair of the Foundation for International Security from 2000 to 2007.
She was appointed Deputy Lieutenant of County Tyrone in 2010;[5][7] she is also a freeman of the City of London and a member of the Peggy Guggenheim Collection Advisory Board.
[5] In 2013 Patrick lent his DNA to a University of Strathclyde study that confirmed his descent from Walter Stewart, 6th High Steward of Scotland.
Thus he was the senior living member of the royal Stewart family, descended in a legitimate male line from Robert II of Scotland.