The UK Office for Nuclear Regulation (ONR) has established, and has the responsibility of maintaining, a UK State System of Accounting for, and Control of, Nuclear Material (SSAC) as required by the UK’s Voluntary Offer Agreement (INFCIRC/951) with the IAEA. To perform this role effectively, the ONR has implemented a structured approach to building its personnel capacity and capability. This structured approach recognised and utilised international good practices and involved an analysis phase, design phase, development phase, delivery phase and includes continuous evaluation. Using this approach, the ONR has been able to analyse the tasks involved in maintaining an SSAC; undertaken a training needs analysis to identify relevant skills/knowledge/experience and captured these within competencies; developed training plans with measurable outcomes; delivered those training plans; and continuously evaluates their effectiveness. Alongside developing a safeguards training framework, the ONR has also produced safeguards-specific guidance and modified existing cross-organisational guidance where applicable to recognise safeguards as a regulatory purpose within the organisation. This allows for a proportionate, consistent and transparent approach to safeguards regulation in the UK. This paper explains the structured approach ONR has taken to build and maintain its personnel capabilities and demonstrates how it supports a functional SSAC. This paper also comments on how this structured approach has been implemented and continues to be delivered in a responsive and adaptive manner during the Covid-19 pandemic and the challenges and restrictions that poses.