It seems strange that we should know so little about how Victorian cities were actually made. We know far more about the total effort that went into making them and the impact this had on the course of investment - perhaps on the very growth of the national income - than we do about the way in which these cities were literally pieced together. It is true, just the same, that no one has yet been able to say with real conviction whether, or to what extent, the growth of her cities in the nineteenth century of itself stimulated or retarded Britain's general economic expansion. Yet what seems in some ways more remarkable than our ignorance on these bigger questions is the smallness of our knowledge about a number of little things, especially those involved in the basic developmental processes of converting open country into closed-up streets and of the business operations that carried them through. Here is an industry - to consider it for a moment at large - which in the first Census of Production in 1907 accounted for about £80 million output per annum, or nearly as much as the whole of the clothing industry, appreciably more than that of gas, water and electricity undertakings combined. We know more about the movements of some of the prices of the factors involved in the productivity of the house-building industry itself than we do about its structure and its ways of working.