There has been a marked increase in the use of quantitative evidence to inform UK higher education policy, with reporting requirements for universities set to rise further. This drive for evidence based policy-making has created tensions within the regulatory structure leading to, for example, the Office for Student (regulator) removing the Quality Assurance Agency for Higher Education from its position of Designated Quality Body (DQB) for England (effective from March 2023), which depending on the perspective taken was either a side-lining of expertise or in response to an apparent failure to provide definitive evidence-based judgements. In this paper we focus on the evidence basis for actions related to the key government policy objective of reducing the degree awarding gap (attainment gap) between students with a range of protected characteristics and those without, including those between BAME (Black, Asian, and other) students and white students. Understanding how evidence is used in this context has clear normative value, but it also has implications for how legislation (Equality Act 2010) is implemented. Through and in-depth analysis we highlight a number of shortcomings in the gathering and use of evidence to inform decision making. Currently, the evidence base for action is the awarding gap for ‘good degrees’ which whilst useful we argue provides a misleading picture of student performance across the sector. We propose an alternative approach which allows a wider use of the available evidence. We test this idea on a Jisc (UK digital, data and technology agency) dataset of 4.5 million students across 10 years along with a more fine-grained analysis of a typical HE institution.