Thanks again.
Eric, I think it would be easier to go back to Iceland next February and re-take the shot, standing a foot or two further to the right! I will turn my attention to the pano, which is huge (by my standards, anyway: 25k x 8.6k pixels).
Phil, there was really nothing magic in the processing. Basic stuff in Lightroom, b&w conversion using Nik SFX pro, then take both as layers into PS and set the b&w to luminosity blend (now I know about that technique, I'm delighted with the results). The effect seems usually to be a bit strong, so decrease the opacity of the b&w layer to taste and brush bits of it away using a layer mask.
Then post here and get told about dust spots.
If you look at the recent thread
here in which I asked about blending, you'll see that there are other ways of getting a similar result, including plugins from Topaz which people who know what they're doing value highly.
Jeremy