David Mitrany was the first Professor appointed in the School of Economics and Politics.
From the Oxford Dictionary of National Biography:
[David] Mitrany worked towards the development of effective peace organizations. [...] At the outbreak of the Second World War, Mitrany became a member of the Foreign Office's academic intelligence unit, and as early as June 1941 was setting out an “Agenda of peace making.” In another paper, “Territorial, ideological, or functional organization?” he expanded his own ideas, and at the end of 1942 he resigned to pursue these further. The results appeared in a pamphlet, A Working Peace System (1943), which had an immediate public appeal and was translated into various languages. Mitrany embarked on an extensive programme of lecturing, broadcasting, and writing, with the aim of ensuring that a new peace organization would not be handicapped by a rigid constitution (as had the League of Nations) but would be given the capacity to develop on functional and sociological lines. The validity of the functional approach was accepted and incorporated in the founding documents of the specialized agencies of the new United Nations.