In North West London, health and social care leaders decided to design a system of integrated care with the aim of improving the quality of care and supporting people to maintain independence and participation in their community. Patients and carers, known as ‘lay partners,’ were to be equal partners in co-production of the system.Lay partners were recruited by sending a role profile to health, social care and voluntary organisations and requesting nominations. They formed a Lay Partners Advisory Group from which pairs were allocated to system design workstreams, such as which population to focus on, financial flow, information technology and governance. A larger and more diverse Lay Partners Forum provided feedback on the emerging plans.A key outcome of this approach was the development of an integration toolkit co-designed with lay partners. Lay partners provided challenge, encouraged innovation, improved communication, and held the actions of other partners to account to ensure the vision and aims of the emerging integrated care system were met.Key lessons from the North West London experience for effective co-production include: recruiting patients and carers with experience of strategic work; commitment to the vision; willingness to challenge and to listen; strong connections within the community being served; and enough time to do the work. Including lay partners in co-design from the start, and at every level, was important. Agreeing the principles of working together, providing support and continuously recruiting lay representatives to represent their communities are keys to effective co-production.