Letters from Henn to his brother, Canon Percy V. Henn, in Western Australia on various family matters [originals]. Also, letters to his son John in Kenya, and others (1916-1936), including references to his Chairmanship of the Joint East Africa Board (1926-1929) [photocopies].

Correspondence, memoranda, etc. concerning his association with the Public Relations Office, the Electors' Union, the Tea Board in Kenya, the Joint East Africa Board, and the Tanganyika Tea Board.

Correspondence, notebooks etc. as Chairman of the Joint East Africa Board (1926-1929) and as a representative on the Imperial Economic Committee (1924-1927), the Advisory Committee of the East African Dependencies Trade and Information Office (1925-1935), and the Tanganyika Railway Commission (1930-1931).