There are more than 20 universities nationwide recruiting on the basis of AAA most of which interview none or a tiny proportion of candidates.
Whilst clearly the personal statement plays a part in recruitment and for some the LNAT pays a bigger part, for the most part what these universities are doing is turning the AAA predictions, actual AS and GCSE scores, school reference and contextual information into an overall pattern of school achievement. In doing that they are not all interpreting the same information in the same way.
It is naive to believe that all of these universities are taking a similar mix of academic strength.
In practice this means that some places will only be taking the stronger AAA candidates. Others will be taking a mix of stronger and weaker AAA candidates. That means it is possible to get in to the second institution with less stellar academics.
What it boils down to is this:- Would most candidates with a QMC offer get a UCL offer? Would most candidates with a UCL offer get a QMC offer?
A few years ago the answer would have been obviously no, many of the QMC candidates would not have been good enough for UCL. As I explained that perception of being slightly less daunting generates applications and that in turn allows the university to become more selective. At some point the penny will drop that it is no longer an easier option and at that moment the beauties of Egham will become more apparent. It is also possible that this penny will drop a year or two after it has actually become equally hard to gain admission.
Whether that moment has been reached by adding an A* to the offers, who yet knows, though I suspect not. I think the perception is still that the A* isn't quite a real grade and that is likely to remain so long as Oxford doesn't require it for all courses.
I may have something of a bias towards QMC because I know a number of the faculty. The London effect is such that if one looks down the list, it is clearly stronger than most of the top provincial universities which certainly wouldn't have been the case a few years ago.