In 1986 the Oxford University Institute of Agricultural Economics was amalgamated into Queen Elizabeth House. The Institute, which came into being in 1913, achieved considerable distinction for its work on the problems of British agriculture under the Directorships of C.S.Orwin and A.W. Ashby. The third Director (1953-69) was of a somewhat different stamp. Colin Clark (1905-89), though without formal training in economics, had established himself as a pioneer of national accounting techniques in the Cambridge of the 1930s (he was mentioned in Keynes' General Theory) and progressed to write one of the classic studies of growth (Conditions of Economic Progress). His name appeared prominently in the Meier and Seers book on 'Pioneers of Development' and there have been many other testaments to his international reputation. The Oxford period witnessed famous controversies on population and food supply, the publication (with Margaret Haswell) of 'The Economics of Subsistence Agriculture', and much other work on a wide range of subjects by no means confined to agricultural issues. The essay which is reprinted below originally appeared in the Italian journal Rivista di Economia Agraria (June 1995) as part of a series on major figures in agricultural economics, and was presented at an Agricultural Economics Society conference (Edinburgh, 1998). It is also the basis for a shorter entry in the Dictionary of National Biography, 1981-90 Supplement. The writer spent a considerable part of his early career as one of Colin Clark's research assistants. A number of people have been kind enough to suggest that the essay should have greater accessibility.