Anecdotally again, but at a recent family event a couple of younger relatives involved in recruiting for London based professions, both said that the volume of graduate applications was so high this year that for the first time the initial filter had been Oxford/Cambridge/Imperial and LSE. This obviously did not mean that there would not be good candidates coming out of other institutions, and indeed both admitted that they themselves would not have met current criteria. Just that the graduate job market was so tough that their firms had to limit the numbers they interviewed.
I also heard of another boy selecting a non-RG university over Cambridge, because the particular applied science department was very highly thought of by employers. I would be surprised if many employers now select on "snob" value alone. However if HR departments are inundated, they will want to filoter somehow even if it means sifting out the quirky or the rough diamonds, and more sadly, those who have chosen to save money by going to their local University.