Abstract: Background: The National Health Service diabetes prevention programme in England, (NHS DPP) aims to identify people at high risk of type 2 diabetes (T2D) and offer them a face-to-face, group-based, behaviour change intervention for at least 9 months. The NHS DPP was rolled out in phases. We aimed to elicit stakeholders’ perceptions and experiences of the factors influencing implementation of, and participation in, the programme during the development phase. Methods: Individual, semi-structured telephone interviews were conducted with 50 purposively sampled stakeholders: service users (n = 20); programme commissioners (n = 7); referrers (n = 8); and intervention deliverers (n = 15). Topic guides were structured using a pragmatic, theory-informed approach. Analysis employed the framework method. Results: We identified factors that influenced participation: Risk communication at referral - stakeholders identified point of referral as a window of opportunity to offer brief advice, to provide an understanding of T2D risk and information about the programme; Perceived impact of the NHS DPP - service users highlighted the positive perceived impact on their behaviour change, the peer support provided by participating in the programme, the option to involve a relative, and the ‘knock on’ effect on others. Service users also voiced disappointment when blood test results still identified them at high risk after the programme; and Behavioural maintenance - participants highlighted the challenges linked to behavioural maintenance (e.g. discontinuation of active support). Factors influencing implementations were also identified: Case finding – stakeholders suggested that using community involvement to identify service users could increase reach and ensure that the workload was not solely on GP practices; Adaptability: intervention deliverers acknowledged the need to tailor advice to service users’ preferences and needs; Accountability – the need to acknowledge who was responsible for what at different stages of the NHS DPP pathway; and Fidelity – stakeholders described procedures involved in monitoring service users’ satisfaction, outcome data collection and quality assurance assessments. Conclusions: The NHS DPP offers an evidence-informed behavioural intervention for T2D prevention. Better risk communication specification could ensure consistency at the referral stage and improve participation in the NHS DPP intervention. Cultural adaptations and outreach strategies could ensure the NHS DPP contributes to reducing health inequalities.