Sarah (1763-1800), sixth and youngest daughter and co-heir of John Hussey Delaval, later Baron Delaval of Seaton Delaval and his first wife, Susannah (d. 1783), married George, 2nd Earl of Tyrconnel on 3 June 1780 and had an only daughter who was heiress to the Earl, Lady Susannah Carpenter, who married Henry, 2nd Marquess of Waterford. The Countess of Tryconnel left her husband to live with the Earl of Strathmore but died of a cold on 7 October 1800 at Gibside, co. Durham. She was buried in Westminster Abbey on 4 November 1800, aged 37.
Downman painted oil portraits of various members of the Delaval family, notably Lady Delaval (G. C. Williamson, John Downman, London, 1907, p. 13) and Miss Delaval (op. cit., p. 52). There is a miniature of Lady Delaval dated 1792 in the Victoria and Albert Museum (Salting Bequest P. 87-1910) which is a replica of an oil painting in the National Gallery. Two other miniatures of the Countess of Tyrconnel by Downman were sold in these rooms, 24 November 1981, lot 32 and 27 November 1989, lot 160. A portrait of the sitter's father was sold in these rooms, 30 April 1996, lot 143.