Thanks, ErrolTheDragon. That is also possible. It seemed strange to me to think that out if 44 students for 7 places (all of whom must have at least A star A, A and most have probably exceeded that with two or three A star predictions), they managed to choose three who didn't go on to get the minimum grades. Especially when the ones they pooled obviously made the grades and loads of the ones they rejected would have got three A stars.
This is a college with 80% state school applications. I guess some of those offered might have turned it down and gone to MIT etc instead. Maybe this is what happened. It's not really a course that attracts many internationals though because they don't really teach it as a discrete subject in say, China or the US or even other European countries.
Anyway, the point I'm making really is that, in regard to interviews, you do hear people say, "Ob they know what they're looking for..." But really, I think any student with above the required grades would easily cope there and the rest is largely arbitrary.