In this article, we explore the mathematical content knowledge of one entire cohort of pre-service teachers (N = 107) through analysing their performance in a Secondary Mathematics Audit that was developed for the International Comparative Studies in Mathematics Teacher Training that was initiated by the University of Plymouth. We study how their mathematical content knowledge evolved during their one-year postgraduate teacher education programme by using a pre and post-course test scheme. An interview was also conducted with five selected pre-service teachers to identify how their responses in the post-course audit were influenced by the pedagogical training. The pre-service teachers' responses to the audits and interviews with selected pre-service teachers show that engagement with pedagogical training in the teacher education course improved the pre-service teachers' mathematical content knowledge. This study also reveals the questions that the pre-service teachers had not performed well or shown much improvement during the one-year programme. These questions were beyond the scope of the school mathematics curriculum.