William Forrest Salmon was born in Glasgow, Scotland in 1843, and was articled to James Smith (1803-1863) in Glasgow from c.1857 to c.1862. He then worked as an assistant to George Gilbert Scott (1811-1878) in London from c.1862 to c.1866 and to his father, James Salmon, Snr. (1805-1888) from c.1866 to c.1867. From c.1867 to 1872 he was in partnership with his father and James Ritchie (1835-1910) in the architectural firm Salmon, Son & Ritchie in Glasgow. The partnership was dissolved in 1872 and that year was reformed as James Salmon & Son. Following the death of James Salmon in 1888, William Forrest Salmon continued the practice under the same name. In 1898 his son, James Salmon (1873-1924), joined the office and in November 1903 John Gaff Gillespie (1870-1926) became a partner at which point the practice was renamed Salmon, Son & Gillespie.
William Forrest Salmon was elected a Fellow of the Royal Institute of British Architects (FRIBA) in 1876. He died at his house, Rowantreehill in Kilmacolm, Scotland on 7 October 1911
See: Dictionary of Scottish Architects 1660-1980 [link below]
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