After completing his MSc in Economics at Stirling University, Duncan moved into a management post with ICL in Manchester, where he stayed for four years. He completed his PGCE at Leeds University and took up his first teaching post at Urmston Grammar School in Manchester, where he was Head of Economics.
After managing the Business, ICT and Modern Languages Faculty at Fulneck School in Leeds, Duncan moved to Queen Elizabeth Grammar School, Wakefield, as Head of Economics, where he also coached jujitsu and kickboxing. During his time there he completed an MA in Leadership and Management.
Duncan joined Marlborough in 2014 after two years at the grammar school in Guernsey, where he was responsible for the reporting, data and assessment of their learning strategy. Duncan is a Principal Examiner for Economics.