This article aims to reflect on the experiences and challenges of a mentor, which brought about by subject-specific mentoring within mathematics for English as a second language (ESL) classes for 16-18-year-olds. This article has provided a mentor’s perspective on the enactment of mentoring in a specific context. The author has demonstrated how specific guidance in the mentoring literature may be enacted and provided support. Furthermore, the author emphasized the importance of mentors’ and mentees’ attention to the detail of the particular context, notably – in this case – the issues faced by ESL learners of mathematics in post-compulsory education in England.