There's more to it.
As investor cash pours into London, it pursues desirable areas near the centre - because that's all they can know. The owners living there see leaflets coming through the door offering much more money than they ever believed, so they look to the burbs and find leafy nice areas, then sell up and move.
So there's a wave of concentric circles expanding outwards, and they funnel into desirable areas, which typically have a cluster of well-to-dos already - some kind of connection.
And we're seeing nasty, nasty tactics. A fair number of people in, say, Chelsea (posh), have assets (house), but no cash. So developers are setting up specialist units to lend to them, content in the knowledge that to repay the immense loan and interest, these people will eventually sell their house, with right of first refusal to the lender. Presto - you get hold of an entire row of thirty houses.
I've seen that in action. Nasty.
But the bubble - the people currently being displaced from the centre will not return, as the availability of property will not increase - wealthy people can afford to buy a house, and leave it empty. They don't care. They don't put it on the market. It just sadly sits.
Check out Lancaster Gate in London - lovely area, but emptier than my wallet.