Walter Crum Watson was born in Balerno, near Edinburgh, Scotland on 19 October 1870 . After studying at New College, Oxford, he was articled to Alfred Waterhouse (1830-1903) in London from 1893 to 1896 and remained as his assistant for a further year. He then worked as an assistant to Aston Webb (1849-1930) in London from 1897 to 1899.
Watson was commenced practice as an architect in Edinburgh in 1900. After serving in the Red Cross during World War One, he resumed his practice in 1919. Apart from the design of All Saints Church in Moddershall, Staffordshire (c.1900), his work consisted mainly of alterations to country houses in Scotland.
He was elected a Licentiate of the Royal Institute of British Architects (LRIBA) in 1911. His address was given as 50, Queen Street, Edinburgh 1914; and Northfield, Balerno, near Edinburgh from in 1934. He died on 10 February 1934
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