Sir Charles Webster influenced both the development of British diplomatic history and the making of the United Nations Charter. He held Chairs at the Universities of Liverpool, Wales and Harvard, as well as the London School of Economics. He served the British government, as soldier, intelligence officer, advisor and diplomat, in both World Wars, attending the Versailles, Dumbarton Oaks and San Francisco Conferences. Although the part Webster played in the creation of the UN has been examined in some depth, his wider thought - historiographical and international - has not been explored. This article aims to address this omission and to assess Webster's practice of diplomacy in the light of his understanding of the diplomatic historian's art.