If you went to DMU or London Met and got a First, then I'd most definitely take a 2:1 graduate from Oxbridge/Russell Group/1994 Group. If we're comparing say a graduate with a First from KCL or Nottingham and an Oxbridge graduate with a 2:1, then it'll come down to other things such as capability, confidence, personality, how they perform in interview, team group tasks, etc. and also the content of the degree if it's a specialist position which requires lots of mathematics/statistics or something similar.
But really, if you go to any Russell/1994 Group university and do well (a 2:1 or First), providing you're an excellent candidate yourself, you'll get a good job and go far if you want to.