This research is a practical attempt to develop academic writing pedagogy at secondary level in New Zealand because from interviews with teachers, personal experience and literature in the professional journal for teachers of English in New Zealand, English in Aotearoa, it appears that this would be a useful enterprise. Literature relating to this, and extending to the related contexts of the UK and Australia has been reviewed. The approach taken is an investigation of top-rated senior secondary writing in subject English, using elements of Hallidayan Systemic Functional Grammar (SFG). The concepts of SFG chiefly drawn upon, namely, Theme and linguistic metafunctions, and their application to the data are presented and explained. This grammatical model was chosen because it allows the interface of grammatical structure and linguistic function to be explored, which in turn permits insight into how the qualities of top-rated writing may be formulated grammatically. This insight may then become part of teaching resources in academic writing by way of both pre- and in-service training material for teachers. Over 100 top-rated English literature essays (graded by teachers) were collected from students, via their schools, so that the data obtained were authentic. Two samples were collected: timed and untimed writing. Each sentence of each essay was typed into one of nine Microsoft Excel spreadsheets, representing locations within the essay. The nine locations were: three introduction locations: initial sentence, medial sentences, terminal sentence; three paragraph locations (all paragraphs in the body of the essays, not introductions or conclusions): initial sentence, medial sentences, terminal sentence; and, three conclusion locations: initial sentence, medial sentences and terminal sentence. The initial grammatical elements and their metafunction(s) for each sentence were categorised. Percentages in each category for each location were calculated so that individual locations could be compared for grammatical and metafunctional characteristics. Grouped locations were also considered where this seemed felicitous; for instance, introductions were compared to conclusions or medial sentences compared to boundary sentences (initial and terminal). Comparisons were also made between the timed and untimed samples. The results showed that some grammatical structures could be associated with particular grouped locations and metafunctional characteristics were not independent of location. The research was also able to suggest grammatical means to achieve metafunctional effects that align with descriptors for writing given by examination boards. For example, clear, logical organisation of writing is highly valued by examination boards. This is achieved by means of elements that perform the textual linguistic metafunction. A variety of grammatical elements to perform this function and their most prominent locations were identified. It is intended that the findings may be a highly directed way to help teachers address some of the writing challenges faced by their students at secondary level.