HIV incidence has decreased in England by over a third since 2019. Despite the early success of HIV Pre-Exposure Prophylaxis (PrEP) in reducing HIV transmission in the United Kingdom, many people who could benefit from HIV PrEP do not yet know about it, or know how to access it. This paper presents the findings of the first England-wide national peer-to-peer based diffusion model to disseminate information about PrEP. Ask Me About PrEP (AMAP) was a 5-month pilot programme which commenced in November 2021. Volunteer mobilisers were encouraged to use their existing knowledge of their communities and geographical areas to assist them in discussing PrEP with their peers. 12 enrolled mobilisers took part in three project evaluation focus groups between November 2021 and March 2022, and five AMAP project staff took part in one focus group in March 2022. Additionally, descriptive statistical analysis explored volunteer mobiliser recruitment to the AMAP project, demographical data of project staff and volunteer mobilisers, volunteer mobiliser attrition rates, and the project's impact. 96 volunteers enrolled, completed training and volunteered as mobilisers. Thoroughout the project, mobilisers engaged their peers in 11,889 conversations about PrEP through individual conversations, online group conversations, online workplace educational events, and social media. The focus groups enabled key stakeholders to reflect on their experiences of the pilot programme. Four key themes were identified during the focus groups: motivations to mobilise and recruitment experiences; training, learning, and materials; mobilisation activity; and support and social networking. Our evaluation demonstrates that peer-to-peer diffusion models used to increase awareness of HIV PrEP in key unreached groups, offer an acceptable public health intervention model for volunteers and project staff.