Linguistic studies of mass media discourse prove that it presents a complex blend of verbal and visual characteristics. To this end, the methodological procedures should also imbibe structural methods combined with cognitive modelling. These forms of text and its analysis tend to be unjustly given less attention in educational process although teaching media literacy has already become a popular trend. The present paper is aimed at investigating the level of students’ awareness as far as certain semantic and semiotic elements are concerned, and to show the methodological steps, students can further rely on. As one of the sources, frequent in modern British mass media discourse, we have chosen criminal conceptual metaphor applied to Jeremy Corbyn. Thus, we show both the linguistic analysis procedure and the results of the pedagogical experiment. In our linguistic investigation we applied a combination of cognitive and structural linguistic methods. For teaching purposes, an experimental linguistic database of verbal and polycode texts was formed. The procedure described herein can be applied in various pedagogical cases: for teaching students of linguistics, journalism and mass media communication studies, pedagogics, politics, cross-cultural and linguocultural studies. The results of the analysis contribute to the investigations of political metaphors and broaden our understanding of polycode mass media texts.