Millett was British High Commissioner to Cyprus 2005-2010 and Ambassador to Jordan 2011-2015. He became Ambassador to Libya in July 2015. Millett has been a columnist for First Rate (at Lloyd's) Arabiya News since 2013.
He has also written for the Jordan Times.
In November 2013 Millett tweeted that Khartoum airport was the "worst airport in the world", causing some debate as to whether his comments were inappropriate given his diplomatic position.