He established and was CEO of the NHS Purchasing & Supply Agency (NHS PASA) from 2000 – 2006. The Agency was responsible for providing national level purchasing and strategic procurement direction to the NHS in England, in order to obtain best value from a £14 billion per annum spend.
From 1990 – 1992 Duncan was Chief Executive of South Bedfordshire Health Authority at the time of the original NHS purchaser/provider organisational division which saw the creation of health services commissioning and the establishment of NHS Trusts and GP Fundholding.
In 1992 Duncan was appointed Chief Executive of the Bedfordshire Health Authority which was involved in merging three health authorities into one. The main functions were to purchase healthcare on behalf of its 540,000 residents, to manage the contracts and the primary care practitioners.
Duncan is a past president of the Chartered Institute of Procurement and Supply (CIPS) and the Health Care Supply Association. He is now also a non-executive director and advisor to several healthcare and public sector related companies, and banks and has been a member of two Treasury OGC Procurement Capability Review Teams.