Sidney Williams was born in Cardiff, Glamorgan, Wales in 1872. He was articled to John Price Jones. He also attended Cardiff University. He commenced independent practice as an architect in Cardiff in 1893 and was for some years in partnership with his father, Robert Williams. In the early 1930s he was senior partner in the firm S. & V. Williams.
He was elected a Licentiate of the Royal Institute of British Architects (LRIBA) in 1911. He was was a member of the Cardiff Architectural Society and its President in 1920.
Williams remained in practice until at least the early 1930s. His address was given as Rectory Road, Cardiff in 1911 and 1914; Borough Chambers, Wharton Street, Cardiff in 1914 and 1930; Westgate House, Westgate Street, Cardiff in 1932; and 95 Colum Road, Cardiff in 1933. He died on 28 February 1933.
Virgil Street Schools, Cardiff; Three schools at Whitchurch, near Cardiff; library at Whitchurch near Cardiff; Carlton Restaurant, Queen Street, Cardiff.
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