I got into Oxford, Durham, Bristol, UCL, LSE, and Manchester for law with 7A*s and 3.5 As at GCSE. I know someone who was rejected from Manchester with AAAA at A-level for having a B in maths GCSE though. I think the general rule for Oxbridge is 5A*s+ and the rest As with the odd B in an unimportant subject. But thats after they take your school into account, so if you went to a crap state school it would be lower, a top private school higher, and probably about 8A*s in the most competitive colleges.