Davidson Nicol, 70, a doctor, writer and former Sierra Leone diplomat who for 10 years headed a U.N. training institute. Since 1985, Nicol had been a lecturer at Cambridge University’s Center of International Studies, living part of the year in his hometown of Freetown, Sierra Leone. He also taught at the University of South Carolina. He was Sierra Leone’s ambassador to the United Nations from 1969 to 1971. He later served as ambassador to Britain, Norway, Sweden and Denmark. From 1972 to 1982, he served as an under secretary-general of the United Nations and executive director of the U.N. Institute for Training and Research. He published two books on U.N. diplomacy and, under the pen name Abioseh Nicol, he was one of Sierra Leone’s best-known fiction authors. His prize-winning work included “The Truly Married Woman,” “The Devil at Yolahun Bridge” and “The Leopard Hunts.” He returned to Freetown in 1958 when Sierra Leone gained self-government, followed three years later by full independence from British colonial rule. In London of cancer Sept 20.