The sitter was the son of George Brudenell, 3rd Earl of Cardigan and his wife Lady Elizabeth Bruce, daughter of the Earl of Elgin. He was brought up at the family estate, Deene Park, in Northamptonshire and married Lady Mary Montagu, younger daughter of the Duke of Montagu who lived nearby at Boughton. Through this marriage he and his wife eventually came into that great estate as well as Montagu's London property. In recognition of his position he was created Duke of Montagu of the second creation in 1766. Their only son predeceased them and the title became extinct. He was succeeded as Earl of Cardigan by his brother James Brudenell in 1790.