Margaret Reeson began work as a teacher in New South Wales in 1957, and between 1961 and 1978 served as a missionary and teacher in the Highlands of Papua New Guinea, with a special interest in illiterate women and youth. In 1979 she moved to Canberra, and graduated with an MA from the Australian National University in 1996. She has been active in the Uniting Church in Australia, and was Moderator of the New South Wales Synod from 2000 to 2002.
During the 1980s Reeson began writing full time, and from her experiences she wrote a social history book about the effect of Christianity on Papua New Guinean people, Torn Between Two Worlds (1972). Reeson also wrote A Very Long War : The Families Who Waited (2000), about the experiences of the families of men missing in the New Guinea Islands during World War 2, many of whom never returned.