Reginald Thelwall Longden was born in Burslem, Staffordshire, England on 21 May 1879. He was articled to John Lewis in Newcastle-Under-Lyme from 1896 to 1899 following which he worked as his assistant until 1901. Longden established his own independent practice in Burslem, Staffordshire in 1901. From c.1924 to c.1938 he was in partnership with William James Venables (1894-1958) as Longden & Venables.
Most of Longden's architectural projects were undertaken in Staffordshire. These included the Liberal Club in Hanley; schools in Leek and Newcastle-under-Lyme; a library and hospital in Burslem; a mining village in Whitfield; offices, warehouses, shops, a café, theatre and cinema in Stoke-on-Trent; the offices of an insurance company in Burslem; and numerous private houses. A drawing and ground-floor plan of a house at Congleton, Cheshire, designed by Longden is featured in 'The Studio Yearbook of Decorative Art' 1908 (illustration B45); a photograph of an entrance hall designed by him is illustrated in 'The Studio Yearbook of Decorative Art' 1909 (p.16); a drawing of two plans of a house in Wolstanto, Staffordshire designed by him is illustrated in 'The Studio Yearbook of Decorative Art' 1910 (p.52); two drawings and plans of a house at Knypersley and 'The Brampton', Newcastle-under-Lyme, designed by him are illustrated in 'The Studio Yearbook of Decorative Art' 1911 (p.50); and a photographs of the entrance front and dining room of'Evernsley', Newcastle-under-Lyme, Staffordshire, is illustrated in 'The Studio Yearbook of Decorative Art' 1914 (p.34); photographs of Leek Golf Club club house, 'Deepdale', Birchall in Leek, 'High Barns' in Leek, and 'Sandiacres', near Leek designed by him, are illustrated in 'The Studio Yearbook of Decorative Art' 1925 (pp.12, 53, 54); photographs of a bungalow in Birchall in Leek, and 'High Barns' in Leeds designed by him are illustrated in 'The Studio Yearbook of Decorative Art' 1926 (pp.30, 56); photographs of a house at Alsager in Cheshire and a fireplace in a house in Newcastle, Staffordshire,designed by Longden & Venables are illustrated in 'Decorative Art' 1927 (pp.36, 55); and a photograph, floor plan and brief description of a house on the Birchall Estate in Leek, Staffordshire, and a kitchen in an architect's house, designed by Longden & Venables are illustrated in 'Decorative Art' 1931 (p.14, 64).
Longden was elected a Licentiate of the Royal Institute of British Architects (LRIBA) in 1911 and a Fellow of the Royal Institute of British Architects (FRIBA) in 1921. He exhibited at the Royal Academy in 1909. Longden's address was given as Market Place Burslem, Staffordshire, and St. Edward Street, Leek, Staffordshire (1909); York Chambers, Wolfe Street, Stoke-on-Trent, Staffordshire, and St. Edward Steet, Leek, Staffordshire (1914); and Stafford Street, Hanley, Stoke-on-Trent, Staffordshire, and St. Edward Steet, Leek, Staffordshire (1926). He was the first President of the North Staffordshire Architectural Association in 1925.
In addition to his work as an architect, Longden designed interiors and furniture. He died in 1925. He died on 27 September 1941. His death was registered in Newcastle under Lyme, Staffordshire
Collingwood, Neil. Secret Leek. Stroud, Gloucestershire: Amberley Publishing, 2016. ISBN: 9781445663739, 1445663732
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
‘Obituary’. The Builder vol. 161, 3 October 1941 p. 312