I agree with the other poster.
But, even though A levels are looked at, it's more of the grade they're looking at. They'd only probably look at the subjects if they were stuck between two people. My best friend didn't take exactly stereotypically traditional lawyer subjects at A level (he did A level law), but still managed to sign a contract with a magic circle firm. And apart from that, it's performance at university which comes first and foremost, not A levels.
I'm probably going to be offered a contract with a good commercial firm in the summer. They aren't magic circle (I'd rather not work in a magic circle firm anyway) but have a good reputation, get interesting cases, money is good, and has actual interesting and fun lawyers. They don't even ask about A levels because their philosophy is at age 17/18 you shouldn't have been sat in your bedroom working hard so you could become a lawyer in another five years time, you should have been out respecting and enjoying your youth. I could not work in a firm where the lawyers lives revolve around their career and law. Would be soul sucking. I guess it all depends on the firm.