As we have already noted, expanded systems of higher education are generally differentiated ones, in terms of their functions, their institutions and their programmes, and the populations they serve. Scott has described the evolution of UK higher education systems from pre-binary, through binary and unitary to market systems (Scott, 2004). Such system evolution is accompanied by system differentiation and, as Teichler has pointed out, differentiation may be realised through ‘types’ of higher education institutions, ‘curricular approaches’, ‘levels’ of programmes and degrees, ‘length’ of programmes and varied ‘reputation’ and prestige among formally equal institutions and programmes (Teichler, 2004). Trow’s well-known distinction between elite, mass and universal systems (Trow, 1974 and 2005), though often regarded as a model of system evolution was in fact a model of system differentiation as it was perfectly possible for elite, mass and universal systems to exist simultaneously in Trow’s conceptualisation.