Martin (1992: 497):
Systemic approaches to context derive from the work of Malinowski (1923, 1935) who argued that texts have to be understood in relation to their context of situation and context of culture. Malinowski developed these ideas with respect to the problem of translating specific texts in particular contexts, leaving it to Firth (1950, 1957b, 1957c) to develop context more abstractly as a level of language. For Firth, context was one of a number of levels of analysis (alongside grammar, morphology, lexis, phonology and phonetics) required for linguistics to make statements of meaning about text (Firth 1935/1957a: 33).
This is misleading. Firth did regard the text as part of his formulation of context, and he did regard context as integral to the study of language, but the following quote from Firth's A Synopsis Of Linguistic Theory, 1930-1955 makes clear that he distinguished language and context. Firth (1962: 6):
Each function will be defined as the use of some language form or element in relation to some context.
This distinction is borne out by Firth's (op. cit.: 9) description of the constituents of the context of situation:
A. The participants: persons, personalities and relevant features of these.
(i) The verbal action of the participants.B. The relevant objects and non-verbal and non-personal events.
(ii) The non-verbal action of the participants.
C. The effect of the verbal action.
Note that 'participants' refers to the interlocutors and any others relevant to the speech event, not to participants in processes in the clauses of the spoken texts that the interlocutors produce.