Denison earned a bachelor's degree in both mathematics and education from the University of Toronto.[5] He is a Chartered Professional Accountant and a Fellow of the Institute of Chartered Accountants of Ontario.[6]
Denison was the Chair of the Canadian Coalition for Good Governance from June 4, 2009, to June 15, 2011, and a corporate director of since June 23, 2005. He has had an extensive career in financial services within Canada, the United States and Europe, with firms including Fidelity Investments (founded as Fidelity Management and Research Company), Merrill Lynch, S. G. Warburg, Midland Walwyn (bought by Merrill Lynch 2013), and Mercer.