Henry Thomas Keates was born in Pancras, Middlesex [now London], England on 19 June 1839 and was articled to Morphew & Green in London. He also attended classes at the Architectural Association in London. After working as an assistant to William Butterfield (1814-1900) in London for nineteen years, he set up his own architectural practice in Petersfield, Hampshire in 1882.
Keates was a Member of the Society of Architects (MSA). His address was given as 23 Crawford Street, London in 1889; and 15, High Street, Petersfield and Trafalgar House, Petersfield. He died in Petersfield, Hampshire on 7 April 1918
Collyers, Petersfield, in conjunction with Robert Bateman; stabling and water tower, Pierrepont, Frensham, Surrey; Broxhead, Alton; Post Office and Board Schools, Petersfield, and Board Schools, Sheet; several residences In neighbourhood; Isolation Hospital Ward, Petersfield
Directory of British Architects 1834-1914. Compiled by Antonia Brodie, et al. Volume 1: A-K. London; New York: British Architectural Library, Royal Institute of British Architects/Continuum, 2001