I can't comment on your childhood in Stockwell, of course, because I wasn't there. But I think I'm reasonably well qualified to comment on the Brixton that I've lived in for some time now.
Of course, I recognise that people tend to mix mostly with others in a similar postion to them and of course this happens in Brixton in spite of the diversity of income and social groups that make it up. But the groupings of haves/have-nots, or old-timers/recent arrivals, or whatever, don't align in any clean cut way with attitudes to Brixton and its other residents or views on gentrification. To write off the whole of a nominal "middle class" as ignorantly prejudiced barbarian occupiers with no regard or concern for those less fortunate than them, no interest in or thought about what's happening in Brixton and how they fit into it...it's just preposterous! Sure there are people moving in who might fit some of that description, but to just lump together a seemingly definable group to create yourself an imaginary and conveniently demonic enemy, well, it's a fiction and a very unhelpful one too because I don't see how alienating those who might be very genuinely interested in trying to reduce the impact of what's going on at the moment is going to get us anywhere.