Thanks Izzie for that. C&C always welcome. The 'nothingness' of the Irish summer encouraged me into my study rather than the great outdoors this morning and I re-worked the sky based on the original JPEG which seemed to be entirely burnt out. Interestingly, and surprisingly, by using curves I was able to recover a small white cloud but had to re-invent the blue for the sky. For this I used Curves again separately for red and green channels. I used heavily feathered rectangle selection (I usually prefer this to Gradient) to keep the sky white near the horizon. A bit of pulling and dragging with Stamp tool and slight deepening of shade in the buildings and this is the result.