In terms of land area, urbanization has undoubtedly been the main generator of changes in land use over the greater part of the present century. Even so, our urban-orientated society, with some 80 per cent of the population living in adminis? trative urban areas, may tend to over-emphasize the scale of this change because of constant contact with, and therefore awareness of, the processes of urbanization in action. Visually, urban growth, even more than afforestation, is a fundamental and distinctive alteration in the landscape which it is unlikely that the eye can overlook; and consequently any superficial assessment of the extent of new urban develop? ment is profoundly conditioned by qualitative rather than quantitative judgments. Such appraisals, which are often additionally charged with emotional attitudes, can, and frequently do, lead to an almost complete obscuring of the actual facts of the situation as far as the extent and rate of change are involved. It is, therefore, essen? tial for any objective evaluation of shifts between the major uses of land to have reasonably accurate statistical information of what is in fact happening in the country as a whole, and in various parts of it, over an extended period of time. ' Changes of occupancy' data.?The only source of comprehensive information on shifts in the use of land is provided by the ' changes of occupancy' data derived from the agricultural returns submitted by farmers to the statistical branch of the Ministry of Agriculture, Fisheries and Food on June 4 each year. When a holding is found to have altered in acreage significantly compared with the previous year, and when the discrepancy does not represent the interchange of land with another occupier for agricultural purposes, the loss of land is investigated by local officers of the Ministry and a record is made of the new use to which the farmland is being transferred. Gains of farmland from other uses are also recorded. These figures are then aggregated and national totals for net transfers of agricultural land are issued periodically (Best, 1959, chap. 7). Although such figures are available for as far back as 1927/28, it is probable that the earlier statistics are less accurate than those of more recent date. In particular, in the pre-war years only gross changes were calculated and, therefore, an estimate of net losses had to be made. Since the end of the war, however, these statistics have been established on a firmer basis and, in spite of reservations by the Ministry of Agriculture to the effect that the figures are approximate only and should be treated with some caution, it would seem from data collected by local planning authorities and from other sources (Best, 1959, p. 84; Agricultural Land Service, 1958) that they provide a reasonably correct statement of