In the old days, if they really wanted you, they would make your place conditional on three Cs or even lower.
What happens now if you do really well in their own admission tests, and have done well in school, the school sing your praises to the skies, and you have a fab personal statement? 
Do they still say they want three A*s? And let you slip through their fingers if you fuck mess up one of your A level exams and get a B?