Brian Hannan completed a PhD in organic chemistry from The University of Auckland in 1973. He began his working life at Fletcher Holdings Limited and in 1977 joined Dow Chemical in Canada; ultimately becoming a global operations manager at the head office in the USA.

In 1981 he returned to Fletcher Challenge holding positions in business development, manufacturing and general management. During the 1980s he worked in investment management and owned a manufacturing/distribution company.

In January 1991 Brian became managing director of newly formed Fletcher Challenge Methanol Limited following the purchase of energy assets from the New Zealand government. Global market leadership was achieved through the reverse takeover of NASDAQ‐listed methanol company, METHANEX, a company which Brian became CEO and deputy chairman of and then retired from in 1995, returning to New Zealand with his family.

During his time in the USA, Brian also completed business studies at Harvard Business School.