Thomas de Grey (1717–1781) was the first surviving son of Thomas de Grey MP of Merton (1680–1765) and Elizabeth Windham (1693–1735/36) of Felbrigg, Norfolk. In 1746, he married Elizabeth Fisher (d. 1750), daughter of Samuel Fisher of Bury St Edmunds, which brought him a considerable estate. Following his father’s death in 1765, he also inherited Merton Hall, Norfolk.

Born into a prominent Norfolk family, de Grey served as captain in the Western battalion of the Norfolk militia under George Townshend, 1st Marquess Townshend with whom his father-in-law wrote a disciplinary tract for the militia. In 1759, de Grey marched down to Portsmouth with his regiment and soon after became lieutenant colonel. When Townshend succeeded his father in the peerage, he recommended de Grey as his parliamentary successor. De Grey stood unopposed as MP for Norfolk in 1764. He stood again four years later and retained his seat after a long and expensive contest. In the following years his health started to decline and he decided not to stand again. He died in 1781 and Merton Hall passed to his nephew Thomas de Grey, 2nd Baron Walsingham.

Much like RN45 of George Townshend, this portrait shows de Grey atop a hill gesturing towards his regiment below. There is nothing to indicate the precise location of the review but it is likely to have taken place not far from Raynham. Documentary sources note that reviews took place at Fakenham and Dereham. There is a print by William Camden Edwards based on the present portrait, or a version recorded by Sir Duleep Singh, at Merton Hall.¹