Mr Lehmann is a senior career officer with the Department of Foreign Affairs and Trade and was most recently Minister-Counsellor (Governance) at the Australian High Commission in Port Moresby.

He has previously served overseas as High Commissioner to Nigeria and Minister-Counsellor (Development) at the Australian Embassy in Afghanistan.

Mr Lehmann holds a Bachelor of Laws and a Bachelor of Architectural Studies, both from the University of Adelaide, Australia. He speaks French and Tok Pisin.