[1] After graduating, he taught drama at various institutions, including Antioch College in the US (from 1967 to 1968), and Flinders University in Adelaide (from 1969 to 1972) where he also began adapting and directing plays.
[1] Robertson made his first onscreen appearance in 1974, in the television series Rush, and that same year, he also featured in cult Ozploitation horror film the The Cars That Ate Paris.
Robertson has had numerous television guest roles, in series such as Matlock Police, Homicide, Rush, Division 4, Bluey, The Sullivans, Skyways, Cop Shop, Young Ramsay, Special Squad, Carson's Law, Prisoner, Rafferty's Rules, Round the Twist, Neighbours, The Flying Doctors, Ocean Girl, Halifax f.p., Snowy River: The McGregor Saga, CrashBurn and Last Man Standing.
Early films included Petersen (1974) with Jack Thompson, football comedy The Great MacArthy (1975), Fred Schepisi’s The Chant of Jimmie Blacksmith (1978), John Duigan’s Dimboola (1979) and biographical drama Phar Lap (1983).
Later films include 2001 comedies He Died with a Felafel in His Hand alongside Noah Taylor and The Man Who Sued God opposite Billy Connolly and Judy Davis, 2010 drama Matching Jack, 2011 film The Eye of the Storm opposite Geoffrey Rush, and the 2014 Angus Sampson comedy The Mule.