London's more expensive, hence the higher wages; but that's for an 'average' cost of living; you might like to tally up your expenses - which may differ from average ones - and see what effect it might have on you. Apart from that, London has a lot more to offer culturally and historically than Leeds (no offence intended to Leedsites, but London is a great world city), as well as far more job opportunities, should you wish to change jobs again at any stage. Again, though, you need to consider whether these prospects interest you. If you never go to art galleries, for instance, the fact that London has lots of them will be of no importance to you.