Abstract: 

Across the twentieth century, Received Pronunciation (RP), now commonly referred to as Standard Southern British English (e.g., Mompean 2026), has undergone several sound changes. One being the replacement of the alveolar tap [ɾ] by the post-alveolar approximant [ɹ] in intervocalic position following stressed vowels, a process that has received limited empirical attention (Fabricius 2017; MacKenzie 2017, 2025). To address this gap, a spoken archival corpus (1919–1999) was compiled, comprising 163 speakers and 4,648 tokens in word-internal and linking /r/ contexts.

Three complementary analyses are presented. First, a focused study of the 1940s–1960s identifies a period of accelerated sound change, led particularly by middle-aged speakers, interpreted as a shift in the sociolinguistic status of [ɾ] from indicator to marker. Second, a long-term analysis shows that the interaction of decade of recording, phonological context, age and gender significantly condition the trajectory of decline, with marked differences in word-internal context between 1950s-1960s females. A third, ongoing study explores phonological and usage-based constraints. Overall, this sound change reflects broader social and historical developments affecting RP, including dialect levelling (e.g., Jansen & Mompean 2023) and the declining prestige of the upper classes (Fabricius, 2018; Lindsey, 2019; Mugglestone, 2003).