Architect Robert George Thomas won the design competition held in 1864 and construction began in 1865. The church was opened in 1867.
The South Australian Register of April 17,1867, described the church as in the early English Gothic style, with adaptations from the French Gothic. The nave was much wider than usual, while the aisles were narrower, leaving nearly the whole interior open to the view of the minister. There was a tower and spire, partly built, “and the whole of the works are of the most durable and substantial character, none of the walls of the church being less than 2 ft 4 in thick”. The total cost for fixtures and fittings was about £1200. Interior fittings were of Sydney cedar, and a handsome clock was presented by Mr Perryman.
The builders were Brown and Thompson (formerly English and Brown) and the cost was more than £10,000. Carving was done by an Irish mason, Mr Peters. The lengthy report in the Register concluded: “The exquisite beauty and chasteness of the Church have been the subject of remark for sometime past; and now that it is so far completed as to be opened for public worship, its harmonious proportions and grand effect have been admitted by all who have seen it. The building is a real ornament to the City, it is far superior in effect to any other ecclesiastical edifice in the Colony, and does great credit to the architect who designed it, to the builders who erected it, and to the congregation who have been spirited enough to carry it out.”
Stow Church is one of two churches designed on Flinders Street by Thomas. The Baptist Church was built four years earlier in 1861-63.
R.G. Thomas was a son of Robert Thomas of South Australian Register newspaper fame. He arrived in 1836 on the Rapid and was engaged as a draftsman on Light’s staff. He stayed in South Australia for some years surveying the colony, then returned to England to complete his education as a civil engineer and architect. He designed some prominent churches and buildings while at Newport, Monmouthshire (Wales), and the influence of this experience and the architectural aesthetic of the time is evident in the two Adelaide churches.
Following his return to Adelaide in 1860, Thomas joined the public service in 1866. He became architect-in-chief, designing the Supreme Court in conjunction with William McMinn and superintending the erection of the General Post Office. He left this post in 1870. From 1874 until his death in 1884 he was the secretary to the Board of Health.
The church has bluestone walls well dressed with sandstone and the porch detailing is exceptionally fine. The capitals are of Caen limestone (France) and quatrefoils in Bath limestone (England). The contrast between the materials and the crisp detailing and robustly carved relief, all of which remain in good condition, display the virtuosity of the mason's craft.
The building’s interesting composition is a significant departure from the primarily axial Gothic churches, the small aisles behind a well-detailed “screen” of arcading, and the relatively large transepts, achieving a surprisingly intimate interior. The composition, if completed with the spire over the tower as in the original design, would be dramatic, stamping the building as architecturally “fashionable” for the 1860s, even in Britain. It justifiably won the acclaim of critics.