John Baird (called by Gildard 'Primus' to distinguish him from the second John Baird, 1816-93) was born in 1798 at Dalmuir, the son of Thomas Baird, wright, and his wife Agnes. He was articled to a relative, Shepherd, who died in 1818 and Baird, only twenty and just out of his apprenticeship, took over the business and quickly built up a reputation second only to David Hamilton's.
Baird's style is marked by an extreme classical reserve and severity. From the very first his architecture was remarkably mature as could be seen at Greyfriars Church, a design not without originality. His style changed little, the posthumously completed Gartsherrie Office being far more like 1820 than 1860. Only at the McDonald Muslin Warehouses was his commercial architecture notably Italian Renaissance rather than classical. The possibilities of iron made a strong appeal to his essentially practical mind and in 1855-56 he erected the Iron Building on Jamaica Street Glasgow in conjunction with the iron-founder Robert McConnell who held the patents for the malleable iron beams used in its construction. Even in his later Gothic work he clung tenaciously to the style of the 1820s, his mansion at Urie, Kincardineshire (1855) being in the late Tudor idiom evolved by Wilkins and Burn forty years before. He refused to take part in competitions, and earned a reputation for attention to detail, probity and honesty, which brought him many commissions as valuer and arbiter.
In his private life Baird was a mason, Lodge Glasgow St John. A portrait of him by Sir Daniel Macnee (now in Glasgow Art Gallery) bears out Gildard's characterisation of him as 'a large well-built man' who 'had a presence of one that ought to be in authority'. He died at Westfield, Partick on 18 December 1859 and was buried in Glasgow Necropolis (Section Sigma lair 84). He was survived by his wife Janet Bryson or McKean, whom he had married in 1837 and who died on 24 April 1887, and his two daughters, Flora (born c. 1838) and Agnes (born c.1841).
Baird had suffered from chronic brain disease from 1855 until his death and most of the work from that period must have been effectively designed by his assistant James Thomson. Thomson had been born in Glasgow in 1835, the son of Hugh Thomson, builder and Jane Hosie. He had been articled to James Brown of Brown and Carrick c.1850. When Brown inherited the estate of Currie and the partnership was dissolved, Thomson appears to have secured a place in Baird's office, but there may have been an intervening employer as his RIBA nomination paper gives no details. Baird had taken Thomson into partnership in 1858, but the firm did not adopt the style of Baird & Thomson until after Baird died, when Thomson inherited the practice. The delay was probably to avoid confusion with the recently dissolved partnership of John Baird the Second and Alexander Thomson, but the retention of Baird's name after 1859 was not only a matter of continuity but of distinguishing the practice from that of another James Thomson in West Nile Street. Thomson briefly continued Baird's experiments in cast-iron facades with McConnal patent beams in the early 1860s but thereafter his practice, which was amongst the very largest in Scotland, focused on commercial architecture, pioneering the concept of large city office blocks with shops built for rental. These tended to be an astylar Italian Renaissance which became richer in details in the early 1890s, if somewhat repetitive in composition. He was admitted FRIBA on 3 June 1878, his proposers being John Honeyman, John Burnet and Charles Barry Junior.
Thomson married Isobel (or Isabella) Miller Aitken and they had three children: Isobel Thomson (born c. 1868), James Baird Thomson (born in 1869 or 1870) and William Aitken Thomson (born 21 September 1871). James Baird Thomson was probably educated at the Albany Academy, and joined the practice as an articled apprentice in October 1887. He became an assistant in 1891 when he designed the British Linen Bank at Whiteinch and an addition to Crossbasket House. In October 1888 he was joined by his brother William Aitken Thomson, who is known to have been educated at Albany Academy. William became an assistant in 1892 when he undertook the working drawings for the Schaw Convalescent Home at Bearsden, presumably from sketch designs by his father. Both sons were made partners in May 1899.
James Thomson senior died on 12 February 1905 at 30 Lynedoch Street, Glasgow of syncope following a gastric haemorrhage resulting from hepatic cirrhosis, and was buried in Glasgow Necropolis (Section Epsilon lair 444). He left moveable estate of £41,792 1s 4d. His second wife, Margaret Elizabeth Aitken from Torphichen, survived him.
The practice was continued by his sons, both of whom were admitted FRIBA on 3 December 1906, their proposers being James Milne Monro and John James Burnet. Their nomination papers helpfully list their work separately indicating that James Baird Thomson was responsible for the free Renaissance Cambridge buildings and the severe warehouse designs and William Aitken Thomson the German Renaissance elevator buildings. There is no indication of either brother having studied at Glasgow School of Art or having travelled, although William probably had as contemporary accounts correctly state that the details of the Council building were taken from the Ritter Inn at Heidelberg. By 1906 the Clydesdale Bank had became an important client.
Some time before 1914 James Baird Thomson's health failed and he retired to Florida Mount, New Brighton, Cheshire, where he died on 5 June 1917. He was buried in the family lair in Glasgow Necropolis, his gravestone indicating that he had been married to Isobel Aitken Swan. His brother William Aitken Thomson continued the practice from the same office until 1929 when he relocated it to 150 Holland Street, probably to cut costs in the recession. In 1942-43 the practice was taken over by Weddel & Thomson on William Aitken Thomson's retirement. His main client in the inter-war years was the Clydesdale Bank, his last buildings being in a modern manner.
William Aitken Thomson died of cancer of the larynx on 26 November 1947 at 2 Queen's Gate, 125 Dowanhill Street, and was buried in the family lair in Glasgow Necropolis. He was survived by his wife Margaret Watson Christie (who died on 6 February 1952) and a son, Alexander M S Thomson. Another son, William James Thomson, had died on 25 February 1927 at the early age of seventeen.