The sitter was the eldest son of Francis Scott, 2nd Duke of Buccleuch (1695-1751), by his wife Jane, daughter of James Douglas, 2nd Duke of Queensbury. On 2 October 1742 he married Caroline Campbell, eldest daughter and co-heiress of John Campbell, 2nd Duke of Argyll and 1st Duke of Greenwich. They had four sons and two daughters. Lord Dalkeith was elected as Whig Member of Parliament for Boroughbridge on 22 April 1746. On 1 April 1750 he died of smallpox aged 29, and was buried at Dalkeith Palace.