David Cousin was born in North Leith in 1809 (christened 28 May), the son of John Cousin, joiner and his wife Isabella Paterson. He was articled to his father as a joiner but studied mathematics with Edward Sang and early secured a place in William Henry Playfair’s office, exhibiting a design for a parish church in the RSA of 1830. He left in 1831 to commence his own practice from his father’s house at 24 Fettes Row. No executed work is known from the first few years but he competed for the Scott Monument and became acquainted with John Claudius Loudon for whose ‘Cottage, Farm and Villa Architecture’ he made two designs, that for a Scots baronial mansion being advanced for its date.
Around 1837 Cousin moved to 12 Clarence Street on his marriage to his first wife Isabella Galloway (Johnston says Isabella Paterson). They had three daughters all of whom died early: Agnes (born 21 January 1840, died 10 July 1856), Isabella (born 14 April 1842, died 21 February 1874) and Eliza (born 14 December 1845, died 15 May 1850). Shortly thereafter he formed a short-lived partnership (1839-45) with the Glasgow civil engineer William Gale under the style of Cousin & Gale, Cousin being in charge of the Edinburgh office and Gale the Glasgow one. The practice came to wider notice almost immediately by winning two competitions, one for the classical West Church in Greenock and another for the neo-Norman Parish Church at Cambuslang; and in 1841 Cousin was appointed assistant to the elderly city Superintendent of Works, Thomas Brown, at 12 Royal Exchange, with freedom to continue his private practice, which was based at 43 Princes Street from c.1843. Over-commitment in relation to the Greenock Church brought about what was described as ‘brain-fever’ which left his health permanently impaired.
Cousin was one of the most outstanding architects of his generation but because of his recurrent ill-health, preoccupation with civic duties and the nature of his practice, his abilities were never as fully realised as they might have been. In the early 1840s he became a specialist in the layout of cemeteries, most of them with very competent Gothic gates and lodgehouses, and in the case of Warriston, Newington and Dalry catacombs. Like his former master Playfair, Cousin ‘came out’ (left the Established Church) at The Disruption and for the newly formed Free Church he prepared standard Italianate round-arched designs with low-pitched roofs which could be built quickly and cheaply. They were widely adopted, but it was a matter of some disappointment to him that he was not more widely commissioned when they were replaced by more permanent structures from the 1850s onwards. He did, however, design the most ambitious of the early Edinburgh free churches, St George’s, in the neo-Norman style he favoured in the late 1830s and early 1840s, while Thomas Maitland commissioned him to design the Free Church offices and Savings Bank on the Mound in 1858-63, an outstanding picturesque neo-Jacobean design to enhance the Old Town skyline. The same idiom was adopted at the brilliantly planned curved-frontage India Buildings (1864), by far the most innovative block of business chambers then constructed in Scotland.
In 1845 following the death of George Angus in that year, Cousin became architect to the British Linen Bank, its branch bank building programme becoming the mainstay of his private practice; and on 1 June 1847 he was appointed Edinburgh’s Superintendent of Public Works in succession to Thomas Brown who had retired earlier that year, his first works in that capacity being the magnificent mannerist palazzo of the Corn Exchange in the Grassmarket (1848) and the abbatoirs (1851-52) for which he made a study visit to Paris. The appointment brought with it responsibility for the University of Edinburgh which was then still municipally-owned and resulted in the commission for the Reid School of Music Classroom.
The success of the Edinburgh Corn Exchange with its wide-span timber roof brought commissions for the exchanges at Melrose, Dalkeith and Kelso, the last two having Tudor Gothic frontages which successfully reproduced the qualities of original fifteenth century work. Cousin was also one of the pioneers of Puginian-tractorian early Decorated in Scotland, notably in his churches at Oban (1846) and Rosneath (1853) which reflected his friendship with the Episcopal Church architect John Henderson.
Cousin was a founder-member of the Architectural Institute of Scotland in 1850 and gave a number of papers, the more important of which concerned the chronic housing problem Edinburgh then faced, ‘Remarks on the Domestic Architecture of Paris’ delivered in 1855-65 recording the impressions of his visit of c.1850. A further paper ‘Remarks on Jeffrey’s Theory of the Beautiful’ followed in 1857-58, reflecting his interest in the mathematically-based proportional system whih led him to the founding of the Aesthetic Society. In built form these proportions are particularly noticeable at the Reid Music Classroom (1849), his own house at 7 Greenhill Gardens (1849) and several of his British Linen Bank branch banks.
On Henderson’s death in 1862 Cousin took over his practice and completed the work in hand; but as the practice was predominantly an Episcopal one and Cousin was a Whig Free Churchman, not much of Henderson’s clientele was retained. In the same year, 1862, Cousin laid out the lands of Mayfield in Newington for Duncan McLaren, who was also a Free Churchman. Cousin’s official duties were extended significantly on 18 December 1867 when he was appointed architect to the Improvement Trust he had helped to promote, but in accepting he referred to his breakdown in health and asked that John Lessels be appointed joint architect with him, a request which was implemented on 17 March 1868. Under the Improvement Act Cousin planned St Mary Street, Blackfriars Street, Jeffrey Street and Chambers Street, the architecture of which reflects his transition from pure Italian Renaissance to a mid Victorian freestyle also evident in the later bank-houses.
Cousin resigned as City Superintendent of Works on 23 April 1872 because of failing health but retained his appointment as joint architect to the Improvement Trust. He left for Algiers and Mentone to recover his health but continued for a time in private practice, being among those invited to compete for the University’s new buildings in 1874 when he submitted a joint design with Lessels, now unfortunately lost. Isabella died in December 1876 whereafter he married a Miss Lawson. His later years appear to have been spent mainly in Louisiana in a continuing attempt to recover his health but the practice continued throughout 1875-77 from 9 Coates Crescent. Cousin died on 14 August at The Hermitage, Sans Souci, Baton Rouge, Louisiana. There was no surviving family from either marriage; a brother, George Cousin was an ordained surveyor. Cousin’s pupils comprised John McLachlan, the younger John Henderson and Thomas Kemp, elder son of George Meikle Kemp. The practice was continued by his surveyor brother George in partnership with William Ormiston who was probably largely responsible for the practice in Cousin’s final years. Whether he was a pupil is not known.