There are plenty of places in and around London where you'll find parks and open spaces with mounds that are simply grassed-over rubble (and I'd imagine far more so in German cities). But in postwar austerity it was necessary to raise as much income as possible from exporting whatever they could.
And a footnote: during and after the war, it was found that bomb sites were sprouting with plants that hadn't normally been seen outside railway embankments - particularly rosebay willowherb ("fireweed") and Oxford ragwort, which came almost to be seen as symbolic of the blitz, as poppies are of the First World War (I can remember seeing plenty of those around in the bomb sites that were still awaiting rebuilding in my childhood). I wonder if any of those crossed the Atlantic?
Jeez, I read this with utter fascination and explored and discussed it with others. Totally, fascinating. Thank you for turning me unto this as it is right up my alley and what i yearn to learn more about. Leave it to you K2 to have found this.
Kerouac - you are the wonder of wonders....where do you unearth all this interesting stuff?! Not in a million years would I ever imagined the bricks and mortar of London being in the Americas......But then did you know chips of Roman tiles are here in South Africa - just waiting for geologists and historians to dig up the pieces when I'm gone........