I got 45 through high A plusses, and doing well on the exam, but I wasn't top of the cohort -- apparently I was second. Me and another handful of kids were fighting for the top position all year, but a fair few of them bombed out in the exam -- the next best score was 38 and we were expecting at least another 40. It's not so much how well you do in the SACs, it's more of absolutely blitzing the exam, really.
I forgot to add the thing that makes it hard is that it's so easy -- contradiction, yes, but it's probably true. THAT's really why (I think) it's so hard to get above 40. Every mark you drop in the exam is probably near comparable to dropping a mark in say, Further.
By the way, I back what's been said -- Legal is all about rote learning and how well you can memorise stuff. That is the skin and bones of it. How well you memorise it and what sort of detail you go into, how coherently you structure your answers, how much time you spend practicing writing them, how you identify what examiners are looking for in a model answer -- that's the extra stuff that's also important in doing well.