 Cotton went on to various overseas postings in Australia, India, Malaysia, and London prior to 1970.In 1970, 1971 and 1973, he was an advisor at sessions of the United Nations General Assembly.He served as New Zealand consul-general in New York from 1973 to 1974, and high commissioner to Samoa from 1975 to 1977 and Tonga from 1975 to 1976.