Born in Sydney,[2] and after leaving Manly Boys High School, Divall joined the Australian Broadcasting Commission as a music producer in the early 1960s for nine years before working as a trainee conductor for Opera Queensland.

In 1972, on the invitation of Dame Joan Hammond and Peter Burch, he became the inaugural music director of the Victoria State Opera in Melbourne, where he remained for 25 years.

Divall conducted many concerts, ballets and 151 operas, particularly works of the late baroque, Mozart, Handel, Gounod,[4] Berlioz and Verdi.

As a musicologist he edited over 150 works of early Maltese composers especially from the period of the knights, including the complete sacred music and operas by Nicolas Isouard (1773–1818).

In 2014, he was appointed an honorary research fellow at the University of Divinity, Melbourne, and in September 2014 a visiting professor of music at King's College London.