National exhibitions and festivals perform a number of roles at the same time. In the first half of the twentieth century exhibitions were first and foremost trade fairs, occasions on which to promote British goods but at the same time provide an opportunity for cementing imperial relations. Exhibitions are also sites of aesthetic discourse where, for example, particular architectural or design ideologies may be promoted; in addition, they provide platforms for the conspicuous display of scientific and technical achievement; and finally, they provide opportunities for creating and projecting ideas of national identity, however multi-faceted those might be. Furthermore, in order to encourage the widest possible attendance and popularity, most exhibitions from the late nineteenth century onwards included a large number of purely entertaining attractions, which of course provided places for the mingling of social classes, something that appealed to post-1945 notions of a properly democratic society. Exhibitions therefore always perform a number of functions, some of which may indeed conflict with each other, and need to be analysed on a number of levels.