Paris is the centre of political and economic power in France. During the period 1925-55, not a single institutional innovation or change in state policy could have developed without first being the subject of conflict, experiment and political compromise between members of the ruling elite and the population of the Seine. The engineering and electrical industries of the Seine département (Paris and its bordering suburbs) became a laboratory for official economic and social policy development. Here, these policies took shape, emerged and ultimately acquired their independence.