Years 8, 9, 10 places can be very limited, it will depend on leavers, bed spaces, MDS availability and whether they want you. Elmhurst had extra auditions last summer as they hadn't filled all their places despite high numbers auditioning. I know there is at least a couple of free beds in one of the boarding houses. To be honest it's best not to try and rationalise it, it'll melt your brain, the odds are against getting in later up the school but for some it does happen, it's like a lot of things, right place, right time and it'll come together. From experience keeping at it can also help, they do notice and track some of the candidates they don't initially place.