Here's an incredible photo of London taken by FT ace Izabella Kaminska from outside the FT towers.
Pretty sure there's at least 11 cranes in this picture. Possibly 12.
It's a nice visual description of a phenomenon taking place around the world: In major international cities, money is flooding into real estate as the global super wealthy park more of their assets into real estate. And since prices are going ballistic in London, it only makes sense that tons more supply is hitting the market.