After completing his education – attending Auckland Secondary Teachers’ Training College and gaining a BA from the University of Waikato Barrett held the following positions during his career:
• 1970 Lycee La Perouse, Noumea, New Caledonia, Assistant English Teacher
• 1971-72 South Pacific Commission, Noumea, New Caledonia, Information Officer
• 1973-74 Department of External Affairs, Research Assistant, NZ
• 1975-77 Vice-Consul, New Zealand Consulate-General, Noumea
• 1978-80 Policy Officer (aid to Western Pacific, then UN including UNESCO affairs), NZ
• 1981-84 NZ Second Secretary, Paris
• 1985-86 Senior Policy Officer, UN Affairs, Personnel
• 1987-89 NZ Deputy High Commissioner, Nuku’alofa, Tonga
• 1990-92 Director for Kaupapa Maori, NZ
• 1992-95 NZ High Commissioner, Honiara, Solomon Islands
• 1996-98 Director, Protocol Division, NZ
• 1998-2001 NZ High Commissioner, Suva, Fiji
• 2001-03 Director, Protocol Division, NZ
• 2003-04 Director, Treaty of Waitangi Information Programme, State Services Commission, NZ
• 2004-05 Official Secretary, Government House, NZ
• 2006-2008 Director, Maori Policy Unit, MFAT, NZ
• 2009 NZ High Commissioner, Cook Islands