The historical development of rules of debate in the UK House of Commons raises an important puzzle: why do members of parliament impose limits on their own rights? Despite a growing interest in British Political Development (BPD) and the institutional changes of nineteenth-century UK politics, the academic literature has remained largely silent on this topic. Three competing explanations have emerged in studies of the US Congress, focusing on efficiency, partisan forces, and non-partisan (or: ideology-based) accounts. This paper falls broadly in the third category, offering a consensus-oriented explanation of the historical development of parliamentary rules. Working from a new dataset on the reform of standing orders in the House of Commons over a period spanning 205 years (1811-2015), as well as records of over six million speeches, I argue that MPs commit more quickly to passing restrictive rules in the face of obstruction when legislator preferences are proximate within both the opposition and government, and when polarisation between both sides of the aisle is low. The research represents, to my knowledge, the first systematic and directional test of a range of competing theories of parliamentary reform in the UK context, shedding light on the process of parliamentary reform over a prolonged period of Commons history, and advancing several new measures of polarisation in the UK House of Commons