In London, Alagappan worked for BBC. Remarkably, while working at BBC, Alagappan interviewed a pope. After working at BBC, Alagappan returned to India and became a journalist for The Hindu. He went on to work at the United Nations in Bangkok and transferred to New York in 1961. Alagappan worked at the UN for 30 years and served as the deputy director of the natural resources and energy division.