In this paper, we interrogate and justify the design of a local project that used collaborative design research in a secondary school in England. As authors, we represent teachers and teacher educators engaged in design research, whereby we acknowledge the difficulties implicit to university and school collaborations within a performative culture. Our analysis recognises the struggle for research-informed professional judgement in the decision-making and actions of educators that are situated in schools. A professional learning project is analysed to position teachers and teacher educators as practitioner researchers. In this respect, Stenhouse's work provides an analytical framework that is both a lens through which to interpret the nature of collaborations, as well as a methodology that allows us to understand the way in which we navigate the gap between educators' aspirations and the curriculum design and teaching within the project. The collaborative design research project was stimulated by an aspiration to make trigonometry accessible to low prior attaining pupils in a secondary mathematics classroom. This provides a stimulus for understanding the conditions that enable collaborative lesson inquiry and to question whether it can provoke raised aspirations for young people in inclusive classrooms. This allows us to understand the work of teachers as researchers and research users in an increasingly messy teacher education context. We interrogate the potentially problematic connection between research and practice within collaborative inquiry, as wdecisie understand how we enable research that is "held accountable for its relevance to practice" because "that relevance can only be validated by practitioners" (Stenhouse, 1988, p. 49).