Duncan Lewis AO DSC CSC
Board Chair, Non-Executive Director

Duncan Lewis AO DSC CSC is the Board Chair of Thales Australia, bringing with him a wealth of knowledge and experience acquired over his 47-year career with the Australian Government, both in and out of uniform.


Duncan retired as Director-General of the Australian Security Intelligence Organisation in 2019 following a career that included Commander of Australia’s Special Air Service Regiment, National Security Advisor to the Federal Government, Secretary of the Department of Defence and Ambassador to Belgium, the European Union, Luxembourg and NATO.


He joined the Australian Army after schooling in Western Australia, and graduated from the Royal Military College Duntroon in 1975. His 33-year career in the military culminated in his appointment as Major General, Special Operations Commander Australia.


In 2005, Duncan joined the National Security Division within the Department of the Prime Minister and Cabinet and was appointed as Australia’s inaugural National Security Adviser in 2008. In 2011, building on almost four decades of experience in defence and national security communities, Duncan was appointed Secretary of the Department of Defence.


Late in 2012, Duncan was appointed Ambassador to Belgium, Luxembourg, the European Union and NATO. On 15 September 2014, Duncan was appointed Director-General of Security and head of the Australian Security Intelligence Organisation.


Duncan was awarded Officer of the Order of Australia in 2005 for his service as the inaugural Special Operations Commander Australia.