As an academic economist at the London School of Economics, Trinity College Dublin and the University of Chicago, he wrote and taught game theory, economics of industry and regulation. In government, he oversaw merger regulation, enforcement of competition rules, consumer protection, and credit regulation. He has been a strong advocate for the removal of government restrictions on competition and supply side reforms to improve productivity growth.
John is a member of the World Economic Forum Council on Emerging Multinationals, a member of the Policy Advisory Board at the Social Market Foundation, a member of the Advisory Board at GovernUp, a trustee at Centre for Economic Policy Research, a trustee of StepChange, and Chairman at Kaleidoscope Trust.