Geoffrey Reynolds Barnsley was born at 320 Hagley Road, Edgbaston, Birmingham, England on 5 July 1900. It is not known where or with whom he trained as an architect. He was awarded the RIBA Ashpitel Prize in 1924 and was elected an Associate of the Royal Institute of British Architects (ARIBA) in 1925. He was later elected a Fellow of the Royal Institute of British Architects (FRIBA).. Barnsley was architect to Welwyn Garden City Urban District Council until 1936. A pair of houses in Welwyn Garden City designed by Barnsley are discussed in Small Houses £500-£2500, edited by H. Myles Wright (1927 p.85). In 1945 he was appointed Deputy County Architect for Warwickshire County Architect. and succeeded Charles Henry Elkins as County Architect in 1952
His address was given as Middle Gannaway, Norton Lindsey, Stratford-on-Avon, Warwickshire in 1939. He died in Leamington Spa, Warwickshire on 27 October 1959