Whilst much attention has been paid to the socio-economic gap in higher education participation, far less research has investigated the extent to which graduate earnings vary by their socio-economic background. In this research, we present results from an analysis that uses large scale administrative data from both the education and the tax systems to document the trajectories taken by different pupils through the school system into HE and beyond into the labour market. We then measure how the earnings of English graduates around 10 years into the labour market vary with the socioeconomic background of the graduate. Based on a simple measure of parental income, we see that graduates from higher income families (from the top fifth of the income distribution of those enrolled in university) have median earnings which are around 25% more than those from lower income families. This partly reflects the different subject and institution choices of students from different socio-economic backgrounds. Once we control for institution attended and subject chosen, this premium falls to around 10%. We discuss the interpretation of these findings for policy on fair access to universities whose graduates tend to have higher earnings.