Henry William Mann [also known as Harry Mann] was born in Witham, Essex, England in October 1883. His father was a school master and the family lived in the tied school house on Newland Street, Witham, Essex. He studied at Chelmsford School of Art in Science in Chelmsford, Essex, England (1894-1900), and at the Architectural Association in London. He was articled to Frederick Chancellor (1820-1886) from 1900 to 1902 and remained as his assistant. from 1902 to 1912. He then worked as an assistant to the Essex County Architect, Frank Whitmore.
He qualified as an architect in 1914 and was elected an Associate of the Royal Institute of British Architects (ARIBA) later that year.
His address was given as Chigwell House, Witham, Essex in 1914. He was killed in action in Arras Hautes-Pyrénées Midi-Pyrénées France on 30 March 1918 whilst serving France in the Royal Field Artillery during World War One.
Directory of British Architects 1834-1914. Compiled by Antonia Brodie, et al. Volume 2: L-Z. London; New York: British Architectural Library, Royal Institute of British Architects/Continuum, 2001
‘Obituary’. RIBA Journal vol. 25, 1917-18 pp. 123, 168, 184