Research on political style suggests that where women make arguments that are more emotional, empathetic and positive, men use language that is more analytical, aggressive and complex. However, existing work does not consider how gendered patterns of style vary over time. Focusing on the UK, we argue that pressures for female politicians to conform to stereotypically ‘feminine’ styles have diminished in recent years. To test this argument, we describe novel quantitative text-analysis approaches for measuring a diverse set of styles at scale in political speech data. Analysing UK parliamentary debates between 1997 and 2019, we show that the debating styles of female MPs have changed substantially over time, as women in Parliament have increasingly adopted stylistic traits that are typically associated with ‘masculine’ stereotypes of communication. Our findings imply that prominent gender-based stereotypes of politicians' behaviour are significantly worse descriptors of empirical reality now than they were in the past.