Participation in any kind of mathematical study during upper secondary education in England is significantly lower than in other educational systems. As a result, many English students enter university at age 18 or 19 having not studied mathematics for 2 years or more and relatively large proportions of students entering numerate degree programmes do not have a qualification in advanced school mathematics. To date, the mathematical preparation of those university entrants who do not have an advanced school mathematics qualification has not been documented. This study addressed this by analysing a large dataset formed from the combination of two large national databases in England: the National Pupil Database and the Higher Education Statistical Agency Database (N = 253,557). This dataset provided the school mathematics qualifications of undergraduates from England across all degree subjects, who took General Certificate of Secondary Education (GCSE) Mathematics in 2008 and entered a UK university between 2010 and 2012. The study found that approximately 10% of undergraduates did not have a C grade at GCSE Mathematics, which is commonly assumed to be a minimum requirement for entry to university. In general, degree subjects with more mathematical demand recruited students with stronger mathematical backgrounds: 64% of undergraduates in subjects with high mathematical demand had an advanced school mathematics qualification compared to 24% in subjects with medium mathematical demand and 12% in subjects with low mathematical demand. For some university subjects with high and medium mathematical demand, for example Electronic and Electrical Engineering, there were substantial proportions of students with weak school mathematics backgrounds. There was considerable variation across universities with undergraduates in the high-status Russell Group institutions having stronger school mathematics qualifications within the same degree subject.