This article draws on Foucault's concepts of power and discourse to explore the issues of teaching mathematics to low attainers in primary schools in England. We analyse a data set of interviews, from a larger study, with the mathematics teachers of one child across three years, showing how accountability practices, discourses of ability and inclusion policies interrelate to regulate both teachers and student. We demonstrate the impact of neoliberal policy discourses on teachers' practices and how they are caught up in conflicting ways by an accountability regime that subverts inclusive pedagogies, requiring teachers to monitor, label and assign within-child deficits. In spite of these regulatory technologies we identify contradictory fault lines between mathematics education policy discourses which we argue provide the potential for developing critical awareness of accepted practices and opportunities for change.