The construct of language competence lies at the heart of language education, underpinning key processes such as language teaching and language assessment. Acknowledging its prominent position in the field of language education and seeking to illuminate its nature, this study attempted to trace the historical trajectory of the construct of language competence as operationalised in the context of secondary L1 education in England. Through analysing a sample of high-stakes English tests from 1867 to 2017, it identified the meaning that language competence acquired in the domain of L1 assessment - and, by extension, also in the domain of L1 teaching - at different points in time. The study empirically demonstrates the fluid and evolving nature of the construct of language competence, questioning the legitimacy of attempts to compare language 'standards' in education across time. Also, it provides a historical insight into aspects of secondary L1 education in England over the last 150 years, highlighting the research potential of high-stakes tests as means of accessing information about the direction, emphasis and mission of language teaching in different historical periods.