Background Public Health registrars (SpRs) were an important component of the workforce that contributed to the COVID-19 response. This study explores their contribution and the impact the early stages of the pandemic had on their learning and training. Methods Data were collected from SpRs in the London and Kent, Surrey, Sussex training programme between July and September 2020 through a mixture of questionnaires and semi-structured interviews. A thematic analysis of interview transcripts was undertaken to identify themes. Results 35/128 SpRs responded to the survey and 11 were interviewed. SpRs were placed across a range of organizations and made a significant contribution to the COVID-19 response. Overall, SpRs learned important skills but working on the response may for some have impacted negatively on training. A number of facilitators and barriers to learning were identified. Conclusion The study findings highlight the opportunities for learning created by the pandemic. However, changing projects and the desire of SpRs to contribute to the response meant the impacts on training were mixed. Future deployment of SpRs should consider the balance of responsibility and pace when delegating work, as well as the need to supervise effectively and support remote working to maintain good mental wellbeing.