James Salmon was born in Glasgow on 11 October 1805, the son of John Salmon, a weaver and merchant at Bonhill, Dunbartonshire and his wife Margaret Jackson. He practised in Glasgow from c.1825 and worked in partnership with Robert Black, architect to the Union Bank, from 1843 to c.1854. He married Helen Russell (1817-81) in Edinburgh on 19 March 1837. Of their sons, the younger, James (b. 19 June 1853), trained as an accountant and settled in Australia in 1882, returning only briefly to visit the family in 1887. The elder, William Forrest Salmon, was born in 1843 and sent to the office of James Smith in or about 1857 to train as an architect. There he became acquainted with William Leiper, William Scott Morton and the decorative artist James Moyr Smith, then engaged on the lavish interior work of Overtoun, Dumbarton. On completing his articles Forrest followed Scott Morton to London, securing a place in the office of George Gilbert Scott. He returned to Glasgow in or about 1866 and became a partner in the firm in 1867 or 1868 along with James Ritchie who had been a senior assistant in the office since at least 1862, the practice name becoming Salmon Son & Ritchie. This partnership was dissolved in 1872, the practice name now becoming James Salmon & Son.
In 1868 James Salmon became first President of the newly founded Glasgow Institute of Architects, Alexander Thomson being his Vice-President, and together with his son Forrest was admitted FRIBA on 4 December 1876. They were amongst the first recruits in Charles Barry Junior and John Honeyman's campaign to extend the Scottish membership, their third proposer being Thomas Leverton Donaldson who had Ayrshire connections.
In the meantime, on 12 June 1872 William Forrest Salmon had married Jessie Alexander (b. 1843) at Dalry House, Edinburgh, the home of William Scott Morton who had married Jessie's elder sister Elizabeth (Eliza) in 1867. Jessie died suddenly in Edinburgh on 5 January 1887, while staying with the Scott Mortons. She left two sons - James, born on 13 April 1873 at 12 Seton Terrace, Glasgow, and Hugh, born 16 November 1874. James was initially educated privately and sent to Glasgow High School in September 1883, remaining there until 1888 when he joined the family firm for two years.
The Salmons attracted notable pupils in James Marjoribanks MacLaren and George Washington Browne. Like Leiper, Forrest retained his links with London which were greatly strengthened by the Scott Mortons who expanded their business first to the capital and then in 1889 to New York. These links brought the Salmons into an even wider artistic circle, Forrest's sister Helen Russell Salmon marrying the Yorkshire-born animal painter Tom Hunt, and among their many friends was the London Swedish architectural draughtsman Axel Haig who had accompanied Forrest on his first visit to Italy.
James Salmon (Senior) died on 5 June 1888 when walking home after giving one of his celebrated after-dinner speeches: he also had some reputation as a poet, having written a long pastoral comedy, 'Gowandean', which was illustrated by his friend Sir Daniel Macnee. He left moveable estate of £2,559 19s. 11d.. William Forrest Salmon thereafter continued the practice under the same name.
In 1890 James (Junior) was sent to Leiper's office to complete his apprenticeship, attending the classes at Glasgow School of Art for the unusually extended period of seven years, 1889-95. He left Leiper's office in 1894 at the end of his articles. Leiper's influence on Salmon was to remain marked in both commercial and domestic work. As a twenty-first birthday present Forrest sent him on a Grand Tour of the continent which is partly chronicled in watercolours in the Salmon collection at NMRS made between April and July of that year.
James Junior returned to the family firm in March 1895. By that time, John Gaff Gillespie (b. 1870) was in charge of most of the design work. Gillespie had been articled to James Milne Monro c. 1884, concurrently attending classes at Glasgow School of Art, and had won the Glasgow Institute of Architects prize in 1889 jointly with Charles Rennie Mackintosh. This brought him to the notice of Forrest Salmon who engaged him in 1891. Like Mackintosh at Honeyman & Keppie, Gillespie was given design responsibility very early, notably at the free Flemish Renaissance Scottish Temperance League building in 1893 and the West of Scotland Convalescent Seaside Homes at Dunoon in 1895. In that same year, Gillespie was taken into partnership, the everyday work of the practice having grown as a result of Forrest having secured some of the business of the British Linen Bank, whose architects were usually J M Dick Peddie & Washington Browne.
James Junior worked under his father and Gillespie for rather more than two years, being given much of the design responsibility for Mercantile Chambers on Bothwell Street, a huge project in which the Salmons had a financial interest and which was to become their office. He became a partner in 1898, but for the next few years and even beyond the individual design responsibilities of Gillespie and James Junior are not always easy to separate. Their names were not acknowledged in the practice title until November 1903 when the firm became Salmon Son & Gillespie.