Without opening another can of worms, doors are more easily opened here if you have a 1st or 2:1 from say Oxford or Cambridge, particularly in the City.
From across the pond it looks like the US is worse for this with grads from Stanford, MIT or CMU having a way easier time of it career-wise. It seems a lot easier to get in those "name" companies.
But all this is largely irrelevant, he has the job offer on the table already! That means the Google have placed emphasis on his experience and character rather than where he went to University.
If he was applying to Google, fresh out of University (outside of the so called 'top 10') and was wondering if he was in with a chance, then that would be a different story, but he's proven his worth in the industry already.
I think straight out of university, at least in my experience here in the States, having a degree from a "known" school helps. That said, it does not prevent you from getting good work, especially if you've already built up a social network.
From across the pond it looks like the US is worse for this with grads from Stanford, MIT or CMU having a way easier time of it career-wise. It seems a lot easier to get in those "name" companies.