The distinction between natural sign languages and sign-supported speech is a controversial topic and difficult to assess purely on structural terms because of language contact. Here, we consider British Sign Language (BSL) and Sign Supported English (SSE) with reference to Irvine and Gal's (2000. Language ideology and linguistic differentiation. In P. V. Kroskrity (ed.), "Regimes of language," 35-84. Oxford: Currey) framework on linguistic differentiation. Using interview data from 121 deaf BSL signers from the BSL Corpus, we show that this framework allows us to better understand how BSL and SSE are defined by BSL signers. We refer to the semiotic processes of this framework: iconisation, fractal recursivity, and erasure. BSL, including its varieties, is strongly associated with deaf communities in Britain. Specific grammatical forms in BSL that differ markedly from English constructions are presented as exemplars of sign language use (iconisation), oppositions between deafness and hearingness are repeatedly applied to different social groups (fractal recursivity and iconisation), and occurrences that may not align with this opposition are rarely acknowledged (erasure). We suggest that these semiotic processes are motivated by language maintenance and educational policies. We conclude with a discussion on how deaf signers distinguish between BSL and SSE, suggesting distinctions made are ideologically driven with political and historical roots and better understood from a translanguaging perspective.