Fincham arrived in Victoria in 1852 but did not proceed to build his first Australian organ until 1864. He established a factory at the corner of Bridge Road and Stawell Street, Richmond which was progressively enlarged until it occupied a large block. In 1866, Fincham was awarded 100 pounds by the Victorian Government for establishing the industry of organbuilding in Victoria.
Fincham's instruments were widely sought after and in the ensuing years he built close to 200 instruments for buildings in Victoria, South Australia, New South Wales, Tasmania and New Zealand. His magnum opus was the grand organ of four manuals and 70 speaking stops built for the Exhibition Building, Melbourne and opened in October 1880.
Fincham exhibited instruments in a number of exhibitions both in Victoria and interstate. Invariably they received awards on account of their mechanical and tonal excellence.
In 1882 he established a branch in Adelaide under the direction of his former apprentice Arthur Hobday, who was later to become a partner until his departure to New Zealand in 1897.
In its peak years, the firm built many large organs including Freemasons' Hall, Melbourne (three manuals, 42 speaking stops), The Australian Church, Melbourne (four manuals, 53 speaking stops) and St Kilda Town Hall (three manuals, 37 speaking stops).
Fincham used excellent quality materials in building his instruments. The metal pipework, in particular, was particularly fine, consisting invariably of spotted metal, although Belgian zinc was used for flue basses longer the 4ft from 1880 onwards. His wooden pipework was also skilfully made and voiced.
During the 1880s, Fincham developed and patented a form of tubular-pneumatic action which was used for all large organs from that date onwards. This enabled consoles to be detached from organs, a full range of couplers to be supplied, and pistons to be provided for adding and subtracting stops.
Fincham's later organs displayed a more symphonic tonal palette than those dating from the earlier years of his career. A rich variety of strings and flutes was provided, together with reeds of great vibrancy. The St Mary Star-of-the-Sea church organ is typical of Fincham's later tonal ideals, with its wealth of flute registers, rich foundations and generous provision of chorus and imitative reeds.
While building the St Mary's organ, in September 1899, Fincham suffered a paralytic stroke, from which he made a full recovery. He admitted his son Leslie as a partner in the firm in 1900 which was henceforth known as George Fincham & Son. George Fincham continued to be involved actively as an organbuilder through the first decade of the present century until his death on 21 December 1910.
Fincham was the most important organbuilder in 19th century Australasia. His work output exceeded all of the combined output of the other firms in business. His level of technical skill was such that he could build organs on the grandest scale. In addition, he supplied pipework and parts to organbuilders throughout Australia and New Zealand, and thus the focus of the colonial industry.
The majority of Fincham's larger organs have been greatly altered or destroyed. The organ in the Exhibition Building was broken up between 1948 and 1965 and others have been changed beyond recognition. The only two substantial examples of his later work which survive largely intact are the instruments at St Joseph's Warrnambool (1892) and St Mary's Star-of-the-Sea (restored 1993), West Melbourne.