Nicol was born in September 1924, of African parents. He was educated in Nigeria and Sierra Leone and later at Cambridge University and London University.

He was the first Vice-Chancellor of the University of Sierra Leone, 1966-68; the Permanent Representative and Ambassador for Sierra Leone to the United Nations, 1969-71; High Commissioner for Sierra Leone in London, and Ambassador to Norway, Sweden and Denmark, 1971-72; and Under-Secretary General of the UN, and Executive Director, UNITAR (United Nations Institute for Training and Research), 1979-82. From 1985 he was an Associate Lecturer, Centre of International Studies, University of Cambridge.

He published widely on Africa and the United Nations and also creative writing, under the nom-de-plume Abioseh Nicol.

He died in September 1994.