Introduction: Co-production of health services is becoming more routine with young people but such involvement in research lags behind, especially in the field of health promotion research. Our aim was to co-design and test a community intervention with parents and children focused on changing lifestyle behaviours which might contribute to childhood obesity on a deprived local housing estate in London.

Methods: Within the context of an established integrated care collaborative, we supported parent and child volunteers to co-design and deliver a health and well-being intervention for local children. This was in the form of a 6-week “sprint” of exercise and healthy living activities. The subsequent evaluation was carried out by two children who were trained in basic qualitative and quantitative research methods by us. They designed, conducted and analysed data from intervention participants with repeat follow-up and analysis at 2 years.

Results: Twenty-six children were recruited with 12 completing the programme and 7 followed up for 2 years. Young people aged 12 and older universally felt they could communicate their views better in a focus group led by a local young person with established trust and agency. We observed the value of our peer evaluator’s contribution to the design process and their insights during analysis.

Post programme there were improvements in physical activity and nutrition scores in participants using validated scores, and themes relating to healthy living which were retained at 2 years.

Discussion: The use of participatory evaluation in a citizen-driven intervention allowed us to breakdown barriers such as ?? within hard to reach communities, as well as enabling more meaningful results. We have demonstrated the desirability and acceptability of participatory research with children and young people. This intervention also reinforces that small, community–designed and delivered initiatives have the power to effect behaviour change sustained at 2 years.