In 1956, Watkinson was appointed by Paul Martin to head of Canada's interests at U.N.S.C.E.A.R. – the United Nations Scientific Committee on the Effects of Atomic Radiation. Watkinson spent two years as vice-chairman of this committee. During this time, the Suez Crisis broke out, and another member of the Canadian delegation to the U.N., Lester B. Pearson, proposed the creation of a U.N. Peace-Keeping force, which peacefully resolved the Suez situation and for which Pearson was awarded the Nobel Peace Prize in 1957.