Mr. Hannay was an official representative of the government in discussions that lead to the UK's 1973 entry into what became the European Union. After holding various positions in the foreign office in London during the 1970s and 1980s, he was a minister at the British Embassy in Washington, DC in 1984-1985, and was then promoted to ambassador and permanent representative to the European Economic Community from 1985 to 1990. He spent the next five years as ambassador and permanent representative to the United Nations. Most recently he has taken on specialized roles such as Special Representative for Cyprus between 1996 and 2003 and a member of the UN High Level Panel on Threats, Challenges and Change, reporting to the Secretary-General in December 2004.