Thomas Charles Dagnia was born in Hobart on 12 Dec 1868 to Thomas Campbell Dagnia (1823-1872) and his wife Elizabeth O'Connor. Thomas senior and Elizabeth arrived from Liverpool, England, on the ship Orleana on 3 Jul 1842. He was the ship's navigator. Thomas junior was the only son and youngest of seven children. Tragically, his mother died on 1 Jan 1870, when Thomas was only one year old. His father, a schoolmaster, died on 17 Nov 1872, leaving the family orphaned.
Thomas played the horn in the Tasmanian Exhibition Orchestra in 1891. He played the saxhorn in the inaugural concert of the Orpheus Orchestral Society on 19 Jul 1892, held at the Academy of Music. Thomas was employed in mines before moving to Perth, Western Australia, where he was working as an electrician in 1903. He married Minnie Frances Sara, the daughter of George and Mary Ann Sara, on 6 Jun 1908. Their three children were: Thomas Edward, 1909-1985; Alma Minnie, 1915 and Natalie Fanny, 1917-1977. Thomas spent time prospecting in the Kalgoolie area. He died in Perth on 30 Aug 1939.