The aim of this paper is to provide an insight into the lessons learnt as the primary researcher during an instrumental ethno-case study research project that took place in a mainstream secondary academy that set out to examine the physical education (PE) experiences of adolescent, white, pupils in a 'typical' working-class secondary school (Ayrefield Community School – ACS). With the term instrumental ethno-case study used to reflect the non-continuous nature of the 34 days spent in the school over a 16-month period, the structure and content of the paper aims to provide a greater theoretical and practical understanding of this relatively nuanced and contemporary approach to qualitative research in education. Determined that the study design remained based in ethnography, consideration is also given to the impact of professional and personal time constraints on an ability to engage in a truly immersive ethnographical study. In this regard, the paper also aims to provide additional guidance on the design and implementation of the study and the recording and interpretation of the data for any researcher with similar aims and/or time constraints. In addition, the paper also utilises Norbert Elias' sociological concept of involvement and detachment as the lens through which the juxtaposition between objective researcher and experienced mainstream secondary school teacher was explored and managed throughout the duration of the study. Overall, therefore, the paper aims to provide a theoretical justification for the use of the term instrumental ethno-case study design, additional guidance and lessons learnt on the design and implementation of this approach, and further detail on the extent to which the potential conflict between objective researcher and former school teacher was acknowledged and managed. The project itself primarily set out to examine the physical education (PE) experiences of adolescent, white, pupils in a 'typical' mainstream working-class secondary school (Ayrefield Community School – ACS) and in doing so also sought to explore the attitudes of the pupils in relation to their views on qualifications and education generally, how they spent their leisure time, and more specifically, how their own actions and relationships with their male PE staff came to influence the content and delivery of their PE provision. Therefore, reflecting on the use of the traditional case study methodologies of covert and overt observations, informal guided conversations, and focus group interviews with male pupils and school staff, the paper highlights and examines the practicalities and considerations associated with the selection of, and access to, a 'typical' white, working-class school, how care was taken to encourage 'natural' behaviour during covert and overt observations, the specific nature of informal guided conversations with pupils and staff, and the techniques utilised in order to facilitate focus group interviews with these male adolescent pupils. [ABSTRACT FROM AUTHOR]