Well the free market isnt exactly known for its cornucopia of gifts for the poor - tends to like eating them up and spitting them out. In this case eating up anyone too close to the centre of London and spitting them out as far away as possible.
From what I can see we're in a transition from the soft socialism policies of post WW2 which created one of the things that has given London its character in my lifetime, that of on the whole richer and poorer people living side by side, social planning deliberately tried to mix up class composition of neighborhoods...and we're moving into a new era of London that looks more like cities where the market has been allowed to run free and naturally divide people up on class lines - Paris gets mentioned, but US cities do this the most dramatically by the sounds of it.
We're not there yet but short of a shift in mainstream politics its a done deal. Yes its bigger financial winds that are having an effect, but ultimately its government policy, like knocking down all the social housing in inner city areas (peckham and elephant are ones i know about) and lying about replacing that housing, forcing people on housing benefits out of richer areas with the rate cap, people getting rehoused in seaside towns, refusing to stand up to landlords and property speculators and so on - but its also a more general strategic shift in government policies, which basically no longer even pretend to give a shit about what happens to the poorest. Maybe this is because the so called we're-all-middle-class-now-middle class decide elections, or maybe it was always the case I dont know.
Maybe that Notting HIll film wasn't an embarrassing mistake but a planning document?