While in Italy 1747–54, he visited Naples with James Stuart and Nicholas Revett who were projecting documentation of Athenian antiquities. Brettingham remained in Rome studying architecture and buying works of art for Lord Leicester, Lord Dartmouth, and Lord Egremont. He returned to England via Venice, Vicenza, Germany, and the Netherlands. In Venice his attentions to Palladio were furthered by Consul Joseph Smith. His only securely attributed work of note is the neoclassical rebuilding of Charlton House, Wiltshire (1772–6). Recently discovered drawings led to the attribution to Brettingham of Foots Cray Place, Kent (c.1754–60), based on Palladio's Villa Rotonda, but allowing such culturally embedded forms as the English long hall and a more varied experience of house and gardens.
From The Oxford Companion to Architecture in Oxford Reference.