Glasgow-based firm of architects evolved from Salmon's office under Jack (Giacomo) Antonio Coia (1898–1981—of Italian parentage), who was apprenticed (1915–19) to John Gaff Gillespie (1870–1926). Following Gillespie's death, the latter's partner, William Alexander Kidd (1879–1928), invited Coia to join him, so by the end of 1928, the young man was sole partner in the firm of what was now Gillespie, Kidd, & Coia. Coia won several commissions for RC churches which made his reputation: all were faced with brick (a foreign building material in a Glasgow largely built of brown and red sandstone), and drew on round-arched styles, yet influenced by modern continental design. Among them were St Anne, Dennistoun (1931–3), St Columbkille, Rutherglen (1934–40), St Patrick, Greenock (1935), and St Columba, Maryhill (1937): the last two were not untouched by Expressionism. In 1937 Coia was joined as partner by Warnett Kennedy (1911–99), who was later to claim that he had been mostly responsible for the design of the Church of St Peter in Chains, Ardrossan (1938—which has echoes of the work of Behrens, Östberg, and Dudok), and for the RC Pavilion at the Empire Exhibition in Glasgow (also 1938). The latter building and the Palace of Industries North at the same exhibition marked a pronounced stylistic change in the firm's work.
During the 1939–45 war, Coia, as the son of an ‘enemy alien’, had to close his office: when it reopened in 1945 (the Berlin-born Isi Metzstein (1928– ) joined him as an apprentice), he once more designed several churches, but perhaps only St Laurence, Greenock (1951–4—with its pointed internal arches), is in any way comparable with the pre-war buildings. St Michael's, Dumbarton (1952), is unquestionably a child of its Festival-of-Britain time. During the 1950s the firm became leading exponents of the Modern Movement in Scotland, especially after Andrew MacMillan (1928– ) joined them in 1954. A series of churches, necessary because of the expansion of Glasgow and the building of New Towns, followed, all reflecting modern liturgical ideas: St Paul, Glenrothes, Fife (1956–7), St Charles, Kelvinside (1959–60—influenced by the work of Perret), St Patrick, Kilsyth (1961–5), St Bride, East Kilbride (1963–9—partly demolished), Our Lady of Good Counsel, Dennistoun (1964–6), and St Benedict, Drumchapel (1964–9—demolished) may be cited. The firm also designed St Peter's College, Cardross (1958–66—abandoned), as well as numerous schools, public housing in Cumbernauld and East Kilbride (which has not aged gracefully), and other projects. It was also responsible for extensions to Wadham College, Oxford (1969–70), including the former Blackwell's Music Shop in Holywell Street, and at Cambridge designed Robinson College (1978–81). Virtually every building from St Paul, Glenrothes, was essentially the work of Metzstein and MacMillan.
Gavin Stamp ;Oxford Dictionary of National Biography (2004);Rogerson (1986)