In studies on English phonology it has often been pointed out that sp, st, sk present difficulties of interpretation. In by far the majority of these studies a bisegmental interpretation has been adopted, and the discussion has then turned on the identity of the second elements of these consonant clusters. Should the stop constituents be analysed as /p, t, k/, /b, d, g/, or /P, T, K/ (i.e. archiphonemes)? In the American structuralist school a /p, t, k/ analysis has usually been preferred on the basis of ‘ phonetic realism’ (e.g. Swadesh 1934, Pike 1947, Trager and Smith 1951), but it has subsequently been demonstrated that the stops after s are phonetically more similar to /b, d, g/ than to /p, t, k/ (Lotz et al. 1960, Reeds and Wang 1961, Davidsen-Nielsen 1969). In Praguean phonology, e.g. Trubetzkoy 1939, an archiphonemic solution has been advocated.