I didn't do the A-levels but from my understanding of them I have always thought that they don't seem to discriminate between candidates well enough. That is to say that there just are not enough grades. I think the passing grades you can get are A,B,C or D. Most people who get in to the top universities get straight A's. I think if each of these grades was split in 3 it would make the result a lot more meaningful and would go a long way towards ensuring that the best candidates got invited to study at the university (I think the entire interview process is fraught with huge bias problems).