Duncan has worked on food systems and sustainable diets for over twenty years. In 2020 he founded Nourishing Food Systems working with Rewilding Britain, Greenpeace, The Changing Markets Foundation, Planet Shine, Organix, Merchant Gourmet, McDonalds, WWF, Chatham House, Nourish Scotland and Action Against Hunger. Previously he worked for Compassion in World Farming as head of policy. At WWF UK he was head of food policy and created the programs on sustainable diets and meat consumption. He worked closely with the corporate sector and was seconded to IKEA food for two and half years, and worked with M&S, Sodexo, Tesco, Innocent, Waitrose and Nestle. He is a founder and vice chair of Eating Better and Trustee at Green Planet Ventures