People who had moved there a generation or two before.

Unless you've made it rich, each generation gets pushed out at least a tube zone or two, or to commuter suburbs

The capital has always been home to graduates of top uk schools; the current crop of gentrification has nothing to do with eton or oxbridge. It has to do with petrodollars and securization of the residential mortgage market and with inflationary monetary policy, and globalization of the wealthy upper-middle class. The absolute numbers of elite british students in each class is very small, and london is a very large city. Heck, even the amount of london-based students in the capital is an oder of magnitude larger, and many of them are non-uk or even eu and their rich parents are buying them flats...etc.