Born Lady Catherine Herbert at Arlington Street, St James's, she was a daughter of George Herbert, 11th Earl of Pembroke and his second wife, the former Countess Catherine Vorontsov, daughter of Semyon Romanovich Vorontsov, the Russian Ambassador to the Court of St. James's.
Lady Constance Euphemia Woronzow (1838-1922), married William Buller-Fullerton-Elphinstone, 15th Lord Elphinstone.