British Sign Language (BSL) is a visual-gestural language distinct from spoken languages used in the United Kingdom but in contact with them. One product of this contact is the use of fingerspelling to represent English words via their orthography. Fingerspelled loans can become “nativised”, adapting manual production to conform more closely to the native lexicon’s inventory of phonemic constraints. Much of the previous literature on fingerspelling has focused on one-handed systems but, unlike the majority of sign languages, BSL uses a two-handed manual alphabet. What is the nature of nativisation in BSL, and does it exhibit sociolinguistic variation? We apply a cross-linguistic model of nativisation to BSL Corpus conversation and narrative data (http://bslcorpusproject.org) obtained from 150 signers in 6 UK regions. Mixed effects modelling is employed to determine the influence of social factors. Results show that the participants’ home region is the most significant factor, with London and Birmingham signers significantly favouring use of fully nativised fingerspelled forms. Non-nativised sequences are significantly favoured in signers of increasing age in Glasgow and Belfast. Gender and parental language background are not found to be significant factors in nativisation. The findings also suggest a form of reduction specific to London and Birmingham.