The answer is that it did begin life as a real picture and the base image is this one, taken at sunrise. I enhanced this image a bit in terms of contrast and color, and a few other adjustments. However, not much else.
The image Flux was me centering on the person on the lower left hand side of this, there was something about the color and the silhouette that got me to the point where I thought it made a good base for what became Flux. As for Flux, and the "how" question, the answer is a lot of layers and a lot of time. :-)
Hope everybody is well.