Self-regulated learning (SRL) -- autonomously planning, self-monitoring and self-reflecting on learning -- is a strong predictor of academic success. Mastery of the strategies needed to become a self-regulated learner does not develop automatically in all students; thus, the classroom environment, including pedagogy and modes of assessment, plays a vital role in stimulating SRL. Indeed, the post-16 curriculum in England is often criticised for failing to promote SRL. The Extended Project Qualification (EPQ), however, is a post-16 project-based qualification that has drawn from SRL theories. Research indicates that the EPQ can bolster A-level and degree attainment, yet, the mechanisms underlying this effect remain unknown. This article reports on a qualitative investigation using focus groups and interviews to explore students' and teachers' experiences of the EPQ and its effects on general academic performance. The qualification was seen to promote SRL by building learner agency and self-awareness, and improving engagement. We argue that the EPQ offers solutions for many of the perceived deficits of the English post-16 curriculum and that the decline of the AS-level in England represents an opportunity for learners to fill the 'fourth space' with qualifications like the EPQ, which could empower them to pursue a broad and diverse education.