Duncan also served as a Special Advisor to Phillip Hammond in his then capacity as the Secretary of State for Foreign and Commonwealth Affairs. He was campaign director and office manager for Andrea Leadsom MP from 2010 to 2015 and, before that, was chief executive at MCA Ltd. for five years, a management consulting firm, providing managerial and strategic advice to large companies.
He also worked in European equity strategy for Credit Suisse and JPMorgan Chase in London, and consulted at the World Bank and KPMG in Washington, D.C.
He is a graduate of Georgetown University in Washington, D.C. and Oxford University in the UK.