In 1935, he took a position as organist and choirmaster at St. George's Cathedral in Kingston, Ontario, as well as taking up the newly created post of "resident musician" at Queen's University.

During his years in Canada he still pursued the idea of remaining a performing musician and composer, winning three national composition competitions: for Winter's Poem (1931), Baroque Suite (1943) and Night Hymns on Lake Nipigon (1945).

[4] On a year's leave of absence from Queen's Harrison studied composition with Paul Hindemith at Yale University, also taking courses in musicology with Leo Schrade.

In 1965, he married the noted organologist Joan Rimmer, with whom he collaborated in ethnomusicological fieldwork and its scholarly documentation in a number of common publications.

[6] In 1989, Harry White appreciated Harrison as "an Irish musicologist of international standing and of seminal influence, whose scholarly achievement, astonishingly, encompassed virtually the complete scope of the discipline which he espoused.

"[7] David F. L. Chadd wrote of him "He was above all things an explorer, tirelessly curious and boyishly delighted in the pursuit of knowledge, experience and ideas, and totally heedless of artificially imposed constraints and boundaries.