Margaret Joan Anstee was one of the first women to enter the British Diplomatic Service. She joined the UN as a local administrative officer in Manila, and went on to pioneer many positions previously inaccessible to women over four decades, eventually rising to the rank of Under-Secretary General in 1987. She worked on operational programmes of economic and social development in all regions of the world, mostly with the UN Development Programme, being Resident Representative of UNDP in eight countries, afterwards serving in senior positions at the UN headquarters between 1974 and 1987.

From 1987 to 1992 Anstee was Director General of the UN Office in Vienna, Head of the Centre for Social Development and Humanitarian Affairs and Co-ordinator of UN Narcotic Drug-control programmes. In 1992-1993 she was the Secretary-General's Special Representative to Angola, the first woman to head a military peacekeeping mission. In reitrement Anstee continued to take an active part in the United Nations.