As part of a large pan-European project on co-creating public services we supported the design of a programme in England that attempted to operationalise research on desistance, through a model of co-created, strengths-based working. We then evaluated its implementation and impact. The programme was implemented in a Community Rehabilitation Company. It was delivered in the context of rapid organisational change, often in response to rapidly changing external events and a turbulent policy environment. These factors impeded implementation. An impact evaluation did not identify a statistically significant difference in re-offending rates between the intervention group and a comparator group. However, in-depth qualitative evaluation identified positive examples of co-production and co-creation, with individual case managers and service users supportive and noting positive change. Taken as a whole our findings suggest that a co-created, strengths-based model of probation case management is promising but needs to be accompanied by wider systems change if it is to be embedded successfully.