I'd like to this was totally intentional but actually I was attempting to get a nice clear landscape and soft sky. I was facing directly into the sun so I expected something similar to happen but not quite at the strength which eventually manifested itself. It was a splendid evening and the sky really was this varied and interesting, though not quite as apocalyptic as this image suggests.
Film used Ilford XP2 shot at 200 ISO, rather than the suggested box speed of 400 ISO. This was to overexpose slightly for richer contrast and reduce the grain in the lower light.