Since 1965, British political parties have radically, and repeatedly, changed the ways in which they choose their leaders. In this article, I explain how and why these changes occurred and assess the consequences of the ‘new’ selection procedures adopted by four ‘mainstream’ parties: Labour, the Conservatives, the Liberal Party and the Liberal Democrats. In the first section, following Sjoblom and Stark, I outline a theoretical framework which purports to explain the criteria used by parties in parliamentary systems when choosing their leaders. I then examine the four parties in turn and consider two questions. First, how and why has the process of selecting British party leaders changed over time; and secondly, to what extent, and why, have the ‘new’ selection procedures adopted since 1965 produced different outcomes, resulting in the election of leaders who would not have been chosen had the decision rested with their party's elites and/or MPs alone?