Anstee grew up in Chelmsford, Essex, in rural England. Neither of her parents had finished secondary school, and they encouraged her to complete her education. She was educated at Chelmsford County High School for Girls and Newnham College, Cambridge. She graduated with first class honours in French and Spanish in 1944, although it was another three years before the university began admitting women to full degree status. Anstee went on to continue her studies at the University of London.
Career
After working as a university lecturer, Anstee joined the Foreign Office in 1948. However, due to the Foreign Office's marriage bar policy in force at the time, which required women employees to resign when they married, her career ended with her marriage. Anstee accompanied her husband, a fellow British diplomat, to Singapore and Manila, the Philippines. The marriage began to fail while the couple were based in Manila, and so she took a position with the local United Nations office as an administration officer in order to earn the money for a fare back to England. On her return in 1952, she took a new position with the United Nations. Anstee served successively as Resident Representative of the UN Development Programme in eight countries in Asia, Latin America and Africa. From 1974 to 1987 she occupied senior positions at the UN's New York City headquarters. She was also given major responsibilities in a number of disaster relief operations as well as special assignments for the Secretary-General to assist countries in dire economic distress. In addition, she was involved in the design and implementation of several major reforms of the UN system. She was granted Bolivian citizenship in 1990. Anstee worked on operational programmes of economic and social development in all regions of the world, mostly with the United Nations Development Programme. From 1987–1992 she served as Director-General of the United Nations Office at Vienna, Head of the Centre for Social Development and Humanitarian Affairs and Coordinator of all United Nations narcotic drug-control programs. From 1992 to 1993 she was the Secretary-General's Special Representative to Angola; she was the first woman to head a UN peacekeeping mission. After leaving the UN in July 1993, she served as a Special Adviser to the government of Bolivia on matters relating to development and international finance. In 1994 she wrote a report for UNCTAD on the technical cooperation needs of developing countries in the wake of the completion of the Uruguay Round and led an Inter-American Development Bank mission to Bolivia on socio-economic reform. She wrote and lectured widely on the United Nations, particularly on issues related to development, peacekeeping, and UN reform. From 1996 she advised the Under-Secretary-General of the United Nations Department of Political Affairs, on a pro bono publico basis, on operational aspects of post-conflict peace-building. She also chaired the Advisory Board of the Lessons Learned Unit of the UN Department of Peacekeeping Operations, and for some years actively took part in practical training in peacekeeping techniques for both military and civilian personnel, including simulation exercises, in the UK, Sweden, South America and the United States, South Africa and other African countries. Anstee established the Margaret Anstee Developing World Fund to assist graduate students at Newnham College with their fieldwork. During the last three years of her life Margaret Anstee arranged to have weekly Welsh lessons in her home in Knill in the Welsh Marches. An essay portraying her by her Welsh tutor won a prize at the National Eisteddfod of Wales in 2019. Anstee died in August 2016 at the age of 90.
Gate of the Sun: a Prospect of Bolivia was published in Great Britain by Longman in 1970, and was later published in the United States under the title Bolivia: Gate of the Sun by Paul S. Eriksson. Orphan of the Cold War: the Inside Story of the Collapse of the Angolan Peace Process 1992–1993, was published in the UK and the US in October 1996. A Portuguese translation was published in Portugal in April 1997. Her memoirs Never Learn to Type: A Woman at the United Nations was published in May 2003 by Wiley. In 2009, she published a book The House on the Sacred Lake, describing her life in Bolivia. Anstee also wrote a biography of John Brande Trend, one of her professors at Cambridge. It was published in 2013 as JB — An Unlikely Spanish Don: The Life and Times of Professor John Brande Trend.