The real story is one of intensification. Before 2000-or-so there weren't many sky-scrapers in the City-of-London (i.e the central financial district), now it looks like there are upwards of twenty.
Similarly in almost every photograph there is much less brown/grey space. Either empty spaces, or inner-city car-parks have been replaced by parks, or by new buildings.
I think this is reflected in the population history of the city. Since 2000 the city has grown from 7.2 million to 9.0 million - that's a good 20%, and London within the city limits (not that this is a great measure of city size) now actually had more population than New York.