Gillows supplied a closely related 'Mahogany Looking Glass frame for plate' to the 5th Duke of Rutland (1778-1857) in February 1821 for £4.7.10. The sketch is illustrated in their Estimate Sketch Book for that year no. 3086 (now in Westminster City Library).
A related mirror, attributed to Gillows, was sold anonymously, Christie's, London, 14 September 2004, lot 31.
(See also lot 1163 in the sale).