In that case the first guy who did the aptitude test today scored the highest in the initial test? I could see that working from the initial test onto the aptitude test, however it wouldn't work for the interview. If the aptitude test is sat individually then they can't be ranked until everyone has done it, and i'm sure they'll have to conduct some interviews concurrent with the aptitude test.
Has anyone got a call at all for the interview yet?
Or does anyone know roughly how many candidates attend each stage? The email says 2nd interview in may, do KA give you a book to study for the technical interview?