Notting Hill hasn't always been posh. Neither has Chelsea for that matter. These places have changed in a few generations, but pockets of the original communities remain. If people stay in communities, they can get support from family and friends (apparently some people call this kind of thing 'the Big Society').
Concentration of jobs in London has meant house prices have increased and 'gentrification' has spread, but should that really mean that everybody else has to get booted out?
I have cycled 7 miles to work to get to my job. However, unfortunately, 7 miles from London isn't far enough away to find affordable housing, so that wouldn't do me much good if I were working in a low paid job.
Now if only they hadn't sold all the council houses...