Inequality in college attendance is a key driver of intergenerational mobility. We focus upstream to examine how elite high-schools – specifically UK private (feepaying) schools – shape university destinations across the achievement distribution. Using linked-administrative data, we show the main advantage conferred by private schools is not access to elite colleges for their best students, but that lower-achieving students are more likely to ‘overmatch’: lower-achieving pupils from private schools enrol in university courses around 15 percentiles higher ranked than similarly qualified state-school students. Examining mechanisms, we show that this overmatch is driven largely by differences in application behaviour.