I am acquainted with a disproportionate number of Oxbridge grads, mainly through my old school, which has always targeted those universities for its boys. While everyone is smart and pleasant, there is the constant reinforcement that Oxbridge grads seek each other out throughout their lives to almost exclusively hang out with each other. I mean, as towns they're not exactly next door, but in London there is the joint…
What you do notice though, is they absolutely know how to work their asses off. They're constantly organising things, writing stuff, offering to edit and help develop other people's work, coming up with new ideas and sharing them. They know how to dig deep into a topic and root out the interesting, fun and unexpected, and do something with it.
There are other people in the community who are much the same, it's a very collaborative community. It's not that they're the only people who stand out, but they're right up there.