Henrietta was the youngest daughter of Thomas Butler, 6th Earl of Ossory, and a sister of James Butler, 2nd Duke of Ormonde, a well-known Jacobite nobleman. Her mother, Emilia, was a Dutch noblewoman; Henrietta was thus a first cousin of her husband, whose father was Emilia's brother. They were married on 12 January 1697 and had the following issue:[2]
Henry (1697–1718), styled Viscount Boston
Thomas (1700–1730), styled Viscount Boston, who died unmarried.
Lady Frances de Nassau d'Auverquerque (died 1772), who married Captain (later Lieutenant-Colonel) William Elliot of Wells, and had one child who died in infancy
^L. G. Pine, The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 48.
^Hugh Belsey, ‘Cowper, George Nassau Clavering, third Earl Cowper (1738–1789)’, Oxford Dictionary of National Biography, Oxford University Press, Sept 2004; online edn, Jan 2008, accessed 26 April 2010