 There, having left his Commons post, in 1964, he engaged in researching the papers of J. C. C. Davidson full-time between 1965 and 1968.In 1968, he became Director of the Institute for the Study of International Organisation at the University of Sussex, before moving to work as Principal Officer in the Executive Office of the then Secretary General of the United Nations, Kurt Waldheim, in 1973.While at Sussex, he wrote a revisionist biography of Winston Churchill's years between 1900 and 1939 that argued that there were substantial reasons for Churchill's judgement to be questioned by his contemporaries.