Advancing the concept of populism as a political style, this study compares the debate performances of two British party leaders, Nick Clegg and Nigel Farage, as they clashed in a pair of televised debates over Britain’s EU membership ahead of the 2014 European Parliament elections. The argument tested is that under certain conditions, mainstream politicians will adopt a populist communication style while retaining a non-populist agenda. A mixed methods approach combines computational text analysis with a qualitative rhetorical analysis to demonstrate how the populist and non-populist style can be distinguished and systematically compared. The results suggest that Clegg, although maintaining a non-populist ideology, adopts features of the populist style after losing the first debate. Farage’s communication style, conversely, remains stable to the point of statistical significance. This suggests that one explanatory factor for populists’ success is the consistency of their message and rhetorical delivery, helping bolster their perceived authenticity.