This was taken standing on Three Mills Lane, near Bromley-By-Bow Station, London. If you're a regular user of the District Line (the east end anyway), I'm near the graffiti that you see opposite the water between West Ham Station and Bromley-By-Bow. Oh, and you're looking at Bow Creek.
I watched this guy for quite a while, I have no idea what he was searching for.
If the sky is the same colour as the border, then you're not looking at it at the right angle or maybe your screen settings are different (when viewing this, it shouldn't have big blocks of black or white). Do a screen check. :)