Thomas Dinwiddy was born in Clifton, Gloucestershire, England on 7 May 1845. He was articled to Alfred Cross (1830-1882) in 1859 and remained with him as his assistant until 1866. In 1866 he established his own architectural practice in Greenwich, Kent [now London] and by 1910 was in partnership with his three sons, Tom Norman Dinwiddy (1874-1945), Donald Dinwiddy (1872–1937) and Conrad Hugh Dinwiddy (1881-1917) as Thomas Dinwiddy & Sons
Thomas Dinwiddy was elected a Fellow of the Royal Institute of British Architects (FRIBA) in 1900. His address was given as 12 Peter Street, Bristol in 1851; 16, Nelson Street, Greenwich, Kent [now London] in 1871; 12 Crooms Hill, Greenwich, Kent [now London] in 1881 and 1920; 14 Hyde Vale Cottages, Hyde Vale, London in 1883; 54, Parliament Street, Westminster, London in in 1900 and 1923; St. Margaret's-at-Cliffe, near Dover, Kent in 1926. He died in St. Margaret's-at-Cliffe on 21 March 1928. A road, Thomas Dinwiddy Road, in Lewisham, London. was named after him.
Mansion at Hayes, Kent: alterations to mansion at Mount Coote, Ireland; Roan Girls' School, Greenwich; Greenwich Union In Urinary; Deptford Baths and wash-houses; conversion of former pauper schools at Epsom into infirmary, for Metropolitan Asylums Board; new workhouse at Grove Park; homes for pauper children at Sidcup, Kent.
Directory of British Architects 1834-1914. Compiled by Antonia Brodie, et al. Volume 1: A-K. London; New York: British Architectural Library, Royal Institute of British Architects/Continuum, 2001
Rimel, Diana. Thomas Dinwiddy, a forgotten architect. Lewisham, London: Lewisham Local History Society, 1994 [ISBN: 9780950826240, 0950826243]