Yeah, look at the wiki link in Boo's sig for a clearer picture - but there's one thing I'll say even though I know it's in the wiki: Wadham makes very high offers. My ex-girlfriend is studying PPE at Wadham. She was taking four A levels and her offer was, I think, AAAB, and I think they even specified a couple of subjects that she had to get the As in. I assume that they don't discriminate against you if you're only taking 3 A levels, of course, seeing as some schools won't let you take 4. But if you do decide to apply to Wadham you may wish to bear their extremely high offers in mind.