Elites and Brexit: Ideological Realignment in the House of Lords, 2000-2020


The UK House of Lords has increasingly attracted public attention due to several government defeats of Brexit bills. Despite this growing attention, there is little research on how coalitions’ and individuals’ voting behavior in the upper house of the UK Parliament has transformed since its major reform in 1999. This paper addresses this gap by shedding light on the transformation of Lords’ voting behavior between 2000 and 2020. We argue that the British party system’s growing bipolarity along the UK’s future relationship with the EU had substantive repercussions for decision-making processes in the Lords. Analyzing about 2,400 roll call votes with Optimal Classification (OC) ideal point estimation models, we show that, in the post-Brexit period, partisan clusters among peers dissolved and new voting coalitions emerged, leading to an increasingly unidimensional voting space in the Lords. Our results suggest that the UK’s second chamber has undergone a process of ideological realignment after the 2016 Brexit referendum.