Aim This paper aims to explore patient and public representation in a NHS clinical commissioning group and how this is experienced by staff and lay members involved. Background Patient and public involvement is believed to foster greater public representativeness in the development and delivery of health care services. However, there is widespread debate about what representation is or what it should be. Questions arise about the different constructions of representation and the representativeness of patients and the public in decision‐making structures and processes. Design Ethnographic, two‐phase study involving twenty‐four observations across two types of clinical commissioning group meetings with patient and public involvement, fourteen follow‐up interviews with NHS staff and lay members, and a focus group with five lay members. Results Perceptions of what constitutes legitimate representativeness varied between respondents, ranging from representing an individual patient experience to reaching large numbers of people. Consistent with previous studies, there was a lack of clarity about the role of lay members in the work of the clinical commissioning group. Conclusions Unlike previous studies, it was lay members, not staff, who raised concerns about their representativeness and legitimacy. Although the clinical commissioning group provides resources to support patient and public involvement, there continues to be a lack of clarity about roles and scope for impact. Lay members are still some way from constituting a powerful voice at the table.