He was the eldest son of Matthew Brettingham the Elder and worked also in Palladian style.
He travelled to Italy in 1747, where he purchased sculptures and artwork for his British patrons, including Thomas Coke, 1st Earl of Leicester.
North and Brettingham had met as young men in Rome.
The value of the appointment fell after the passage of the Civil List and Secret Service Money Act 1782, and North appointed Brettingham deputy revenue collector of the Cinque Ports, an office which yielded an income of several hundred pounds a year.
In the words of Howard Colvin, "the income derived from his sinecures seems largely to have relieved Brettingham from the need to develop an extensive architectural practice.