Duncan graduated from the University of Otago in 2017 with a Bachelor of Science, and Auckland University of Technology in 2021 with a Bachelor of Laws.  He was admitted to the New Zealand High Court in October 2021.

Prior to working at Fee Langstone, Duncan worked at a full-service firm where he worked on a range of civil litigation matters including debt collection, contract disputes, property disputes and construction. He has appeared for clients in the Tenancy Tribunal, District Court and High Court