His doctoral thesis, supervised by C. K. Stead, was titled Mosaic: a study of juxtaposition in literature, as an approach to Pound's Cantos and similar modern poems.
[5] In 1973, receiving a Fellowship from the American Council of Learned Societies, he studied with Robert Creeley at the State University of New York at Buffalo.
[13] He wrote and edited textbooks (beginning with On Film in 1980) and many academic papers and books (such as Television in New Zealand, which he co-edited with Laurence Simmons in 2004).
(The film-makers include: David Blyth, Vanessa Alexander, Sam Pillsbury, Alison Maclean, Gregor Nicholas, Hester Joyce, Roseanne Liang, Lisa Reihana, Dan Salmon, and Ray Waru.
Academics include Brian McDonnell, Trisha Dunleavey, Simon Sigley, Geraldene Peters, Xuelin Zhou, Margaret Henley, and Lynne Star.)
[21] Horrocks played a central role in the re-discovery of expatriate film-maker, kinetic sculptor and writer Len Lye.
Horrocks wrote a biography of the artist which was a finalist in the 2002 New Zealand Book Awards and has been described by the British journal Sight and Sound as the "definitive piece of Lye scholarship".
[24][25][26][27] In 2012 he wrote the libretto for Len Lye: the Opera, with music by Eve de Castro-Robinson, which was performed at the Maidment Art Centre, with expatriate singer James Harrison returning to New Zealand to play the role of the artist.
[30] Horrocks has been one of the founders of many cultural organisations, including the Auckland International Film Festival (established 1969), Alternative Cinema (1972), Association of Film & Television Teachers (later the National Association of Media Educators, 1983), Artspace (1986), NZ Electronic Poetry Centre (2001), NZ On Screen (2006), and Script to Screen (2009).