If the number was very low then the re-opening of Forest Hill swimming pool might account for a lot of the increase with direct/indirect employment in Sport whether you teach sport/lifeguard/work in the cafe/do the IT etc.
I always see the Labour party as the aspirational party, the Conservatives as the party of the establishment, there is another party I should mention but I forgot their name. I don't think Labour hold the area back if anything it attracts the Prosecco socialists into the area if they feel the area has a bit of an edge but not too much and of course housing is cheaper than the more established areas.