Abstract In this paper we examine the discourses of Primary school numeracy coordinators responsible for auditing, monitoring and supporting their colleagues in relation to the introduction and embedding of the National Numeracy Strategy (NNS) in the UK. Cultural–Historical Activity Theory (CHAT) focuses our analysis on the contradictory coupling of school, NNS and audit systems with our R&D project through boundary objects and crossers. We achieve this through an analysis of the registers and genres adopted in teachers’ reflective discourses, and their relation to contradictory activities. Their often conflicted narratives indicate contradictions between these systems. We find inquiry hybridised with audit and inflected by its collegial negotiation. We also find dialogical inquiry mediated by the collegial discourse of practice, and our R&D group mediated by a critical discourse of reflexivity. The theoretical articulation of the CHAT approach to discourse through Halliday and Hasan's conceptions of register and genre is discussed.