The aim of this thesis is to discover the principle determining factors behind British Design in the 1960's in order to describe and analyse the background and effects of the crisis in Design theory that occurred at this time. This crisis, which meant a questioning of the tenets of Functionalism - the name with which the architectural and design theorists of the 1920's had identified themselves - constitutes, in both theoretical and practical terms, a major development in Twentieth Century Design History and by implication for any Design historical study. The period thus serves as a model for an examination of some major factors pertinent to many Design historiographical problems. The philosophical and stylistic implications of Functionalism, its discrepancies and variations, are noted briefly. A description of their continuation into the 1950's and 1960's is given in which the gap between abstract ideas and stylistic considerations is seen to widen. The critical reaction to Functionalism, manifested in several spheres, is noted and analysed. This reaction stems from an involvement with popular culture as a serious matter for academic discussion and a desire to restructure the value system within which judgements about buildings, objects and other social phenomena are made. This is followed by a survey of the more general sociological changes that occur in the period and the way in which design is modified accordingly, basing itself upon an alternative set of criteria to that of the Design Establishment, and aligning itself with many of the categories established by the above-mentioned critics.