John Thomson King was born in Scotland on 16 July 1904 and was articled to Burnet, Son & Dick in Glasgow from 1923 to 1927. He also attended Glasgow School of Architecture from where he graduated in 1928. That year he was elected an Associate of the Royal Institute of British Architects (ARIBA). He practised as an architect in Glasgow and in 1939 had an office at 111 Union Street, Glasgow.
In 1947 King acquired the practice of James Austen Laird & Partners in Glasgow and subsequently renamed the business J. T. Thomson. Thomas B. Main joined the practice in the late 1940s and Eric D. Ellison became a partner in the 1950s. In 1955 the name of the practice was changed to J. Thomson King & Partners and in 1964 it was renamed King, Main & Ellison. Other partners followed. King retired from practice in 1969 and died in c.1988.