During his long and diverse career, both in his native Australia and in the UK, he was a regular on radio and TV music shows, and recorded many albums as a solo performer or as leader of a group.
He wrote themes for TV shows including LWT's long-running World of Sport,[6] BBC drama series Champion House, and Rediffusion's Sexton Blake.
[11] Another project, which combined his musical skills with art and classic fiction, came in 1978, when he composed a series of songs to illustrate the Lewis Carroll Alice In Wonderland stories.
[13] Harper worked in the UK until 1983, when he decided once again to return to his home in Australia, where he formed the Australian Chamber Jazz Ensemble as a recording and touring group.
He also took up the position of Head of Jazz Studies at Wollongong University's School of Creative Arts,[14] He continued performing live and recording in his later life, and released an album, Images of Australia, in 1997 [15] Some of his incidental music from Doctor Who was later reused, in reorchestrated form, as part of the De Wolfe stock score of Mary Millington's True Blue Confessions (1980).