Policy makers internationally are increasingly preoccupied with the need for education systems to be developed in ways that mitigate unfairness. What is more contestable is what might need to change. In England this emphasis has informed the development of fair access policies that aim to improve the representation of 'disadvantaged' young people of high 'potential' at high status universities. Drawing on research conducted at the inception of one fair access intervention, this paper provides original insights into a process of policy translation that requires multiple encodings and decodings of two constructs that defy ready definition, with their intersection being a particular point of difficulty. Behind the apparent objectivity of commonly used selection criteria sits a process of situated decision-making that incorporates not only the particularities of institutional context and the understandings of key actors, but also macro level pressures that reinforce the need for changes in understandings of fairness at the top.