Background Patient and public involvement in all aspects of research is espoused and there is a continued interest in understanding its wider impact. Existing investigations have identified both beneficial outcomes and remaining issues. This paper presents the impact of public involvement in one case study led by a mental health charity conducted as part of a larger research project. The case study used a devolved model of working, contracting with service user‐led organizations to maximize the benefits of local knowledge on the implementation of personalized budgets, support recruitment and local user‐led organizations. Objective To understand the processes and impact of public involvement in a devolved model of working with user‐led organizations. Design Multiple data collection methods were employed throughout 2012. These included interviews with the researchers (n = 10) and research partners (n = 5), observation of two case study meetings and the review of key case study documentation. Analysis was conducted in NVivo10 using a coding framework developed following a literature review. Findings Five key themes emerged from the data; Devolved model, Nature of involvement, Enabling factors, Implementation challenges and Impact. While there were some challenges of implementing the devolved model it is clear that our findings add to the growing understanding of the positive benefits research partners can bring to complex research. Conclusions A devolved model can support the involvement of user‐led organizations in research if there is a clear understanding of the underpinning philosophy and support mechanisms are in place.