Architect. Photo shows another work of Gunton's in London, "The exterior of Jacob's biscuit factory on Dockhead, Bermondsey. The building still exists, renamed The Italian Building, and with a further two floors having been added." That page names him as working for the firm 'Gunton and Gunton'.
London Deco Flats has a photo of Baron's Keep, Gliddon Road, W14 and gives: "Josiah Gunton (father) Designed a number of Central Halls and various buildings for the Wesleyan Methodists. Strong connection with City of London and business brought him many City commissions. Alderman of the Corporation of London and its representative to the LCC. William Henry Gunton (son) xxxx - 1974.
London Wiki has a page for Josiah with "By 1881 he was living in Hackney and was an architect's assistant. In 1886 he married Jessie Runchman. He was articled to Gordon and Lowther architects and became a partner in 1885. His son William Henry Gunton (1881-1974) joined as partner in 1916 and the firm eventually became Gunton and Gunton. A Wesleyan Methodist, Gunton designed many chapels for the denomination."