His father, Edward Vincent Brenan, worked for many years in Chinese Maritime Customs Service.

Brenan joined the UK Foreign Office in 1903 and transferred to China in 1905 after two years in Siam.

He then served in Tianjin, Fuzhou, Beijing (then called Beiping), Nanjing and Shanghai and other places.

He arranged for the Governor of Hong Kong, Sir Cecil Clementi's official visit to Canton in 1928.

After returning to Britain, Brenan served as a Chinese affairs adviser to the Foreign Office.