Phonological-phonetic sound systems are abstractions away from substance, so while they are grounded in biological capacity, they also reflect phonetically un-natural relationships arising from a variety of linguistic factors. Sociolinguistic variation is one of these non-biological factors. Pilot results of Scottish English derhoticisation and the social distribution of articulatory variation are presented. The patterns are more radical than the systems that are normally examined in research into the grounding of onset/coda allophony. Some speakers are only very weakly acoustically rhotic in codas due to a rhotic articulation being far more delayed than rhotic systems, being in practice covert for sociolinguistic reasons.