The sitter was born in Lisbon, the son of a successful English merchant. Having settled in London by 1730, he married Mercias da Silva, the daughter of a Portuguese merchant. As a director of the South Sea Company (1742-60) and trading in the City of London, he accumulated a considerable fortune, leaving over £250,000 on his death in 1766. Member of Parliament for Tregony (1737-41) and Poole (1741-65), he owned properties in Soho Square, Ealing Grove, Hertfordshire and Northamptonshire.
This picture is very close in both composition and handling to a portrait of the sitter by Ramsay (signed and dated 1746, see A. Smart, ed. by J. Ingamells, Allan Ramsay, A Complete Catalogue of his Paintings, New Haven and London, 1999, p.127, no. 221). The pose derives from van Dyck's Earl of Carnarvon.