In 1958 he was named Dixie Professor of Ecclesiastical History at Cambridge University. He then became an honorary fellow at St John's College, Cambridge, in 1964. A few years later, in 1968, he was elected to the position of Regius Professor of Modern History, an ancient chair, which he held until 1982, and was President of the British Academy during the early 1980s. As vice-chancellor from 1969 to 1971, he guided Cambridge through turbulent times in the late 1960s, including the Garden House riot in 1970. He was also elected president of Cambridge University RFC in 1973.