Possibly either John Alexander, 4th Earl of Stirling (c.1633-91) or his daughter
Judith Alexander (d. 1724), who married Sir William Trumbull (1639-1716) to their son;
William Trumbull (1708-1760) to their daughter;
Mary Trumbull (1741-1769) who married Colonel the Hon. Martin Sandys (1729-1768) to their daughter;
Mary, Marchioness of Downshire, Baroness Sandys (1764-1836);
thence by descent
Bennet & Son, Valuation of Miniatures, Medals & Curios for Captain A Hill of Welford Bray Co. Dublin, 11 December 1896, p.1; 'The Earl of Stirling by S. Cooper / £42'