In this paper, lingua franca communication is understood as involving language contact (cf. Thomason 2001: 21), which results in a linguistic situation characterized by coexisting and competing linguistic features of which speakers may eventually select individual ones for permanent, regular usage. Greek, Latin, and English in medieval British society, especially in London, will serve as reference cases in the first part of this contribution. The second part of this paper will address the similarities and differences between these historical instances of lingua franca communication and present-day English in both a local, South African, and in its global function. The paper aims at identifying the sociolinguistic factors which control(led) the availability of linguistic features and the choices eventually made by the lingua franca's speakers. Factors such as communicative needs, technological facilities and economic power will be discussed as determining standardization as well as self-regulation, which are regarded as simultaneously operating processes.