William Erskine Thomson was born in Edinburgh, Scotland on 23 February 1875 and was articled to Peter Lyle Henderson (1848-?) from 1891 to 1896. He also attended Edinburgh School of Art and Heriot Watt College in Edinburgh After working as an assistant to John Eaglesham (?-1922) of J. & H. V. Eaglesham in Ayr in 1897, and to Maclaren & Mackay in Perth from 1898 to 1909, he set up his own independent practice in Perth in 1909. Prior to this he had collaborated with Robert Forbes Sherar (1862-1943) in submitting an entry in a competition to design the New City Hall in Perth. Their designs are illustrated in British Competitions in Architecture vol. 2, no. 18, September 1908 p. 207.
Thomson was elected a Licentiate of the Royal Institute of British Architects (LRIBA) and a Fellow of the Royal Institute of British Architects (FRIBA) in 1932. Throughout his career as an architect Thomson lived and worked in Perth, where he died on 13 April 1962
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