ABSTRACTIn attempting to account for the relatively late emergence of a powerful workers’ party, students of British political development have advanced two competing explanations. A cultural approach, based on a conversion model of electoral change, argues that Labour's emergence was hindered by the low level of political consciousness among the British working class prior to World War I. According to the contrasting structural approach, which follows a mobilization model of electoral transformation, Labour's slow progress before the war can be attributed to various restrictive features of the electoral system that excluded the party's natural constituency. Through ecological analysis of a set of 'surrogate’ constituencies in the pre‐war electoral system, this paper examines the social contours of political incorporation, and analyses the probable partisan impact of restricted participation. The results reveal deficiencies in the structural approach that can be remedied by reconciling the insights from conversion and mobilization t