We examine the relationship between secondary school attainment and early-career graduate salaries in the UK. Based on literature on grade inflation, we hypothesise that there is uncertainty regarding the quality of the signal communicated by degree classifications, and that secondary school grades can be used as a tool to determine the veracity of classifications. We find that differences in secondary school attainment, expressed in UCAS points, are consistently a significant predictor of salary differences among graduates attaining Upper-Second-class degrees, and some First-class graduates. We estimate predicted probabilities, to predict the likelihood of a graduate appearing in a given salary band based on the combination of their secondary school attainment, degree classification and the university attended. The most common category of graduate in our sample (250 to 325 UCAS points, studied at a Post-1992 institution and attained an Upper Second class) has a 55% chance of attaining a salary less than £20,000 in the 12 months after graduation.