The history of British trade unionism demonstrates that its fortunes are bound up with a variety of interacting factors. Union strength, levels of membership, ability to mobilize and bargaining power, reflects the positions the state takes on employment relations; the attitude of employers and managers; the operation of the economic cycle, particularly the level of employment and the rate of inflation; the composition of the labour force and the structure of employment – historically some groups of workers have demonstrated greater propensity to organize than others, while size of enterprise and concentration of labour have proved relevant. Union strength is also a function of human agency, the quality of leadership at all levels, from head office to workplace, which enables unions to maximize the beneficial aspects of their environment and minimize its unfavourable features (Undy et al. 1981; Bain and Price 1983; Kelly 1998: 24-65).