This article reports a study of acoustic phonetic variation between ethnic groups in the realisation of the British English liquids /l/ and /ɹ/. Data are presented from ‘Anglo’ and ‘Asian’ native speakers of Sheffield English. Sheffield Anglo English is typically described as having ‘dark’ /l/, but there is some disagreement in the literature. British Asian speakers, on the other hand, are often described as producing much ‘clearer’ realisations of /l/, but the specific differences between varieties may vary by geographical location. Regression analysis of liquid steady states and Smoothing Spline ANOVAs of vocalic–liquid formant trajectories show consistent F2−F1 differences in /l/ between Anglo and Asian speakers in non-final contexts, which is suggestive of a strong distinction between varieties in terms of clearness/darkness. There is also evidence of a polarity effect in liquids, with differing relationships between liquid phonemes in each variety: Asian speakers produce /l/ with higher F2−F1 values than /ɹ/, and Anglo speakers produce /ɹ/ with higher F2−F1 values than /l/. The results are discussed in terms of phonetic variation in liquids and socioindexical factors in speech production.