In 2021, Westminster Council, London, piloted a new Community Health and Wellbeing Worker (CHWW) role in the Churchill Gardens council estate. Four CHWWs were assigned to specific buildings on the estate, to proactively visit the same 120 households that they were responsible for, each month, whether there was a clinical need or not. This approach led to many positive outcomes. In households that were visited by the CHWWs, residents eligible for immunizations, screening or health checks were much more likely to receive them, than households that had not yet been visited. Based on this positive impact, the four Primary Care Networks of Westminster (called Healthcare Central London) have recruited a further twenty CHWWs for deployment in January 2024. In order to give households equal chance of receiving the CHWW services, they have been allocated at random to neighbourhoods of 120 households in two wards, Lisson Grove and Paddington Green. Our study will draw on routinely collected data using the Whole Systems Integrated Care (WSIC) data warehouse, to look back at whether households that were allocated a CHWW were more likely, or not, to receive the immunizations, screening and health checks they were eligible for, than households not allocated a CHWW. This robust evaluation of the impact of the CHWWs will help policy makers understand whether lay people from the community can aid the uptake of and access to preventative services. Already there is national interest in the use of CHWWs, particularly ones that have a mandate to visit households even before the residents express any clinical need, because understanding and supporting families before their problems become too big, makes sense for residents and the health and social care system. This has already been seen in many countries around the world, but for England this evidence base is yet to be developed because, until now, there are no services in place such as this.