Last week, when the temperature was in the thirties and your chances of being struck by lightning were zero, the place to be was in a swimming pool 35 metres above the ground.
This is the Sky Pool at Embassy Gardens, part of the luxury highrise cluster at Nine Elms. It consists of 50 tons of acrylic filled with 150 tons of water, strung out between two neighbouring buildings because neither had the roofspace to support it alone. It can only be used by residents who paid full whack for their apartments, and their guests, and for safety reasons no more than 19 at a time. If your head for heights is less secure, or you'd rather not display your swimming cozzie from underneath, a parallel opaque footbridge can be used to access the rooftop bar on one side from the sunloungers on the other.
I wandered in freely round the back of the American Embassy and stood directly underneath in a deep residential canyon where the sun doesn't shine. Of the ten visible undercarriages nobody was swimming, some appeared to be treading water and the rest were simply standing there cooling off and chatting with their friends. I was reassured that they weren't looking down on me because I'd positioned myself in the one place where I couldn't be seen.
At the nearby ground floor oyster bar all the outside tables were occupied by smart diners enjoying the kind of lunchtime menu that majors on whipped feta, monkfish fillet and tonka bean gelato. But by stepping a little further into as-yet-unfinished corners of the site the streets were instead filled with sweaty workmen, dozens and dozens of them, tucking into lunches of something cheaper and more practical. One day Embassy Gardens will only be for the elite, but during its construction phase it has a much broader socio-economic mix.
What you can't yet do is slip through the railway viaduct to the brand new tube station that'll make living here worthwhile. Arch 42 isn't quite ready to connect, but Nine Elms station on the other side is coming along nicely and already presents a visually strong presence, especially the blue nameplates above the entrances to the ticket hall.
As yet Battersea Power Station station isn't as impressive, at least not from the roadside, but maybe you'll be able to come down in a couple of months and check for yourself. Just don't bother bringing a towel and your trunks.