This paper presents a review of political economy studies focused on the quality of governance and, in particular, on the institutions that mould the policymaking process, influencing the risk of sub-optimal policy outcomes. It examines features of the UK Westminster model that amplify the risk of policy failure, drawing on political science literature on the British constitution and empirical, comparative studies of the British macro polity. The paper also discusses the limits and possibilities of institutional reform, including the conditions for and drivers of institutional change.