Dr Sheldon has managed projects across the MoD throughout his career, including in close combat training equipment, communications and IT, logistics management and submarine delivery. He has undertaken targeted reviews into challenged equipment projects and provided assistance and assurance on delivery and technology management. As Head of Cost Assurance Analysis Service, he modernised and grew the team to directly support Chief of Defence Materiel in establishing an affordable Defence Equipment Programme, and in key commercial negotiations on warship construction. Dr Sheldon established the DE&S project controls function, enabling DE&S Transformation. He has headed the Submarine Production Team that delivers the Astute Class and, since 2020, is responsible for all UK submarine acquisition programmes as Director Submarines Acquisition.