He gained employment as a clerk in the South Australian Council of Education's architectural office under E. J. Woods. When Woods was appointed architect-in-chief by the Boucaut government, Smyth was promoted to clerk-in-charge of Woods' office, and de factochief of staff to Woods. His handling of a dispute between the Government and the Kapunda Marble Company over the Parliament House contract brought him to the notice of several government Ministers. Justice Boucaut, when Premier, had also noticed Smyth and had him earmarked for promotion. This was not to happen as soon as expected, as Smyth burst a blood vessel, which necessitated his return to England for a year. In 1886, the Architect-in-Chief's Department was abolished and the Downer government appointed Smyth to the new post of superintendent of public buildings in the Works and Buildings Department, a position which he held until his retirement in January 1920. Although not an architect, Smyth had considerable influence in the design, construction and maintenance of South Australia’s public buildings. A thorough-going patriot, he insisted on the use of Australian and British materials. Public buildings supervised by Smyth include Withall and Wells' Jubilee Exhibition Building, the north wing extension of the South Australian Museum and the Art Gallery of South Australia, the South Australian School of Mines and Industries, the Thebarton Mounted Police Barracks, Port Road, Thebarton, the Margaret Graham Nurses' Home on Frome Road, the Magill Home, the Bedford Park Sanatorium, and the Torrens Parade Ground. He also influenced the landscaping and beautification of the Torrens Lake surrounds and the North Terrace makeover, all with an eye to value for money. Following Smyth's retirement, the Works and Buildings Department was renamed the Architect-in-Chief’s Department, a title it held until 1960. In 1921 Smyth sailed to England with the intention of living there but returned to South Australia in 1923, writing a series of reminiscences of the department and its staff, which were published in the newspapers.
Smyth was always an ardent imperialist, was active in several imperialist and patriotic organisations, and made sure portraits of the monarch were hung in all notable locations within his buildings. Smyth was a founding member of the South Australian branch of the Royal Society of St George. He was also an active Freemason, belonging to the Duke of Leinster Lodge, No. 363. During World War I, he took a great interest in the welfare of serving soldiers, and gave much of his time, influence and expertise to the Cheer-Up Society.
Family
Smyth married Bessie Saunderson Davidson, daughter of John Davidson, of Galashiels and London, on 19 June 1879. Their children were:
Margaret Laidlaw "Madge" Owen Smyth, who married barrister Edward Walter Godfrey of Shanghai, China, on 26 January 1911. She had a son in Shanghai on 23 September 1920.
Trevor Owen Smyth, who was killed at Gallipoli while serving as a lieutenant with the 10th Battalion, A.I.F.
Arthur Gaynor Owen Smyth, who joined the Royal Artillery in April 1916, direct from St Peter's College, and saw service on the Somme, and later in Mesopotamia, where he was promoted staff captain.
They had a home at Davenport terrace, Hazelwood Park. Smyth's brother, Reverend Arthur Owen Smyth, was a curate in Durham, and died at his brother's residence, "Egryn", Kensington Park, South Australia.
