sentences:  After his retirement from public service he taught in Seattle and Bonn.He subsequently returned to St. Andrews and spent the remainder of his life as an independent scholar.He was an advocate of the right of Tibetans to a separate political existence, a case he made in two books, "Tibet and Its History" (1962) and "A Cultural History of Tibet" (1968), and at the United Nations when the issue of Chinese oppression of Tibet was raised by the Irish Republic, represented by Frank Aiken, during the 1959 UN General Assembly debate on Tibet.