Charles Samuel Thomas was born in Swansea, Glamorganshire, Wales on 27 November 1874 and was articled to J. P. Jones & Rowlands in Swansea. He worked as an assistant W. W. Williams until 1902 when he commenced independent practice as an architect in Swansea. From 1908 he was in partnership with Jacob Herbert Jones (1883-1951) and Kildare Stucley Meager (1894-1964) in the architectural firm C. S. Thomas, Meager & Jones in Swansea. By 1926 Meager was no longer a partner and the firm had been renamed C. S. Thomas and Herbert Jones. Thomas and Jones remained in partnership until the former's death.
Thomas was admitted a Fellow of the Royal Institute of British Architects (FRIBA) in 1925. He was also a member of the South Wales Institute of Architects and its President in the late 1920s.
His address was given as Glasfryn Villas Fforestfach, Swansea, Glamorgan in 1911; and Salisbury Chambers, 15 Wind Street, Swansea in 1914 and 1935. He died 18 December 1935. At the time of his death his address was Acremead, Hendrefoilan Road, Sketty, Swansea.
Schools: — at Alltwen, Gendros, and Wern, Glam.; Ragged Schools, Swansea. Cockett Church, Glamorgan Chapels at Rhydyfro, Alltwen, and Pontardawe, Glamorgan Penrhos, Breconshlre, etc. Houses at Pontardawe and Fforest Fach, Glamorgan; Vicarage, Llanwinio, Carmarthenshire. Post Office, shops (Herbert Street). Pontardawe, Glamorgan various business premises, Swansea; Police Court, Pontardawe, Glamorgan; Police Station, Ystalyfera, Glam.organ Police Station, Fforest Fach, Glamorgan.
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