Mr Quinlan was Australia’s Ambassador to Indonesia from 2018 to 2021. Prior to that he was Deputy Secretary, Department of Foreign Affairs and Trade, and Australia's Senior Official to ASEAN and to the East Asia Summit (2015-2018). He was Australia's chief negotiator with Timor-Leste (East Timor) on maritime boundaries (2016-2018). He was Australia’s Ambassador to the United Nations, New York (2009-2015); and Australia's Representative on the United Nations Security Council (2013-2014) and President of the Council in September 2013 and November 2014.
He was Senior Adviser to the Prime Minister on Foreign Affairs, Defence and National Security (2008-2009).
He has held senior positions in DFAT responsible for North Asia; the Americas; Europe; and in management. He was in charge of Australia’s operational response to the East Timor crisis in 1999. He was a lead negotiator for Australia in international negotiations on Law of the Sea and on Antarctic matters. His overseas assignments, prior to Ambassador to the United Nations, have been as Deputy Ambassador in the Australian Embassy in Washington DC and as High Commissioner (Ambassador) to Singapore. And assignments to the Australian Mission to the United Nations, New York; the Australian Permanent Delegation to UNESCO, Paris; and the Australian Embassy, Dublin.
He has also served as Chief of Staff and Senior Adviser to the Minister for Resources; the Minister for Industrial Relations; the Minister for Trade; and the Minister for Industry, Science and Technology.
Mr Quinlan holds a Bachelor of Arts (Hons) from the University of Newcastle and an Honorary Doctor of Letters (Newcastle).
He was made an Officer in the Order of Australia (AO) in 2016.