Thomas Manly Deane [also known as Sir Thomas Manly Deane] was born the son of the architect Sir Thomas Newenham Deane (1830-1899) in Ferney, County Cork, Ireland on 8 June 1851. He studied at Trinity College Dublin where one of the subjects was architecture taught by his father. After graduation in 1872, he was articled to William Burges (1827-1881). in London. Whilst in London he attended the Royal Academy Schools, and at the Slade School of Fine Art, University College, London. He also trained in the studio of Fred Weekes, and studied in France. In 1875 he returned to Dublin where he worked for a year in his father's architectural practice.
In 1876 he won the Royal Academy Travelling Scholarship for an architectural project with the title ‘The Assize Courts of a Large Provincial Town’, and consequently spent eighteen months in Italy in 1877-78. From 1884 to 1899 he was in practice with his father in Dublin. Deane was elected a Member of the Royal Institute of Architects in Ireland (MRIAI) in 1893 and a Fellow of the Royal Institute of Architects in Ireland (FRIAI) later that year.
In addition to his work as an architect Deane was also a sculptor and medallist. He exhibited at the Royal Hibernian Academy in Dublin; the Royal Academy in London; and the Royal Glasgow Institute of the Fine Arts. He was elected a Member of the Royal Hibernian Academy (RHA) in 1910. In 1911 he was knighted for his services to architecture, specifically for the new College of Science and Government Buildings in Dublin which he co-designed with Sir Aston Webb (1849-1930). In the mid-1920s Deane retired to Wales and died in Erw-Lyden, Caernarvonshire on 3 February 1933.
Science and Art Museum, and National Library of Ireland, Dublin; Anthropological Museum and Physiological Laboratory for Oxford University; the McArthur Hall, Belfast (competition); buildings for National Telephone Co. in Dublin. Belfast, and Wavertree; National Hospital for Consumption for Ireland (competition); buildings of Church of Ireland Training Coll., Dublin; alterations and additions to National Gallery of Ireland; work at Sligo and Monaghan Lunatic Asylums; joint architect with Sir Aston Webb for Royal College of Science and Public Offices Buildings, Dublin; numerous private houses; banks, insurance offices, and other buildings in Dublin and elsewhere; colour decorations and mosaics at St. Bartholomew's Church, Dublin, and other churches in Ireland
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