 Cull has also worked more broadly on the history of propaganda, film, television and radio history and the role of mass media as a source for historical study.He is best known for detailed historical studies of the institutions behind public diplomacy and for emphasizing the importance of "listening" as a pre-condition for successful public diplomacy.He coined the term reputational security for a category of enhanced security that comes to an international actor when they are well thought of by external audiences.