Painter. Born in Edinburgh, the son of a surgeon, Cadell travelled in Europe, studying the work of Cezanne amongst others, before returning to Edinburgh. He became one of the Scottish Colourists, with J.D. Fergusson (1874 - 1961), G.L. Hunter (1879 - 1931) and S.J. Peploe (1871 - 1935), who were influenced by the French use of colour. He very much enjoyed the landscape of Iona, which he first visited in 1912 and features greatly in his work. His career was broken by service in World War I. Cadell's paintings feature in the permanent collections of many Scottish art galleries and sell for exceptional sums at auction.
Cadell is buried in Dean Cemetery. His sister was the actress Jean Cadell (1884 - 1967).