Great photo. Really atmospheric. And I really feel the need to listen to 'Animals' again now.
I'm curious about something though. There's so little curvature on that rainbow, I think you must have been using quite a long lens to pick out the detail - in which case, well done for a composition which is unobvious and unusual. What focal length was it?
Great shot with an ethereal feel to it. When I visit London I find it difficult to get to an elevated position for shots. Is this taken from a public building?