John read Philosophy at Trinity College Dublin. He joined Collett Dickinson Pearce (now part of Dentsu) as a grad trainee going on to become a strategic planner. He then went to Oxford for his MBA specialising in risk and the valuation of intangible assets. Upon graduation, he joined PA Consulting as Principal Consultant in the strategy & marketing practice. He subsequently joined J Sainsbury plc as a senior risk manager.
In 2003 he co-founded Purcell & Co, an international advisory firm assisting clients with governance, succession, public affairs and corporate facilitation. They have advised clients in the UK, Singapore, Dubai, Ireland and the Cayman Islands. In 2020 he co-founded Good Governance Capital.