John Millar Watt was born in Gurrock, Scotland, on 14 October 1895, the son of an engineer, and was brought up in Ilford in east London. He studied metalwork the the Sir John Cass Institute, then anatomy under Henry Stabler. Finally he was apprenticed to the advertising agency while taking evening classes at Westminster School of Art.
In 1915 he signed up with the Artists' Rifles, and later served with the Essex Regiment. He was discharged at the end of the First World War and enrolled at Slade School of Art, continuing to work in advertising and supplementing his income by selling sports cartoons to the Daily Chronicle and cover illustrations to The Sphere. In 1921 he created one of the earliest British newspaper strips for the Daily Sketch, originally called Reggie Breaks it Gently, but soon renamed Pop, starring a portly city gent and his family. He continued drawing it until 1949, after which it continued for another eleven years, drawn by Gordon Hogg.
In the early 1950s he mainly concentrated on magazine illustration, but from the mid-1950s he drew adventure stories and painted covers for the Amalgamated Press' Thriller Picture Library, including Robin Hood and Dick Turpin stories. He also contributed to AP's Robin Hood annuals. From 1960 he drew "Royal Daughters", later "Daughters of Adventure", written by Marjorie Coryn, for Princess. In 1963 he drew an adaptation of The Scarlet Pimpernel for the same comic. He provided many illustrations to Look and Learn. He also drew adaptations of classic novels for Look and Learn and Ranger, including Treasure Island (1965-66) and Dumas' Twenty Years After.
He also worked for DC Thomson from 1961, beginning with "The Legend of King Arthur and his Knights of the Round Table" for The Beezer Book. He drew and painted a variety of historical features and spot illustrations for later Beezer Books and Sparky Books into the 1970s. He died on 13 December 1975, aged 80.
- Norman Wright and David Ashford, Masters of Fun and Thrills: The British Comic Artists Vol 1, Norman Wright (pub.), 2008, pp. 103-115
- Alan Clark, Dictionary of British Comic Artists, Writers and Editors, The British Library, 1998, p. 180