It depends on the individual.
When I graduated from Aston in 2010 I was the top student in the entire university. Not just in my subject, but across ALL subjects. I averaged well over 80%. I then went on to blitz MSc Economics at the University of Bristol and now I'm doing a PhD.
Reasons I went to Aston: I had a rough time at college and didn't work very hard in my A levels at all (only got ABBB), and I also needed to stay in Birmingham for family reasons.
Is someone who got a 2:1 from Oxford or Cambridge better than me?! Definitely not. But it completely depends on the individual, which is why employers conduct interviews instead of just hiring on the basis of the CV alone.