In 1969, Harrison was appointed an executive vice-president at the bank's head office in Toronto, and in 1970 was elected a director.

During World War II, he served in Europe with the 1st Canadian Parachute Battalion.

In October 1956 he became chief inspector of the bank, and in December 1956 he became regional superintendent and assistant general manager in Montreal.

In August 1969 he was assigned to the bank's head office in Toronto, where he was appointed an executive vice-president and chief general manager.

He served as a director of Dominion Realty, Royal Insurance, Canada Life, Falconbridge, TransCanada Pipelines, and Western Assurance.