This is an ISO 800 in-camera JPEG. While the high frequency noise is pretty good, I can see a fair amount of low frequency red channel noise (blotchy noise) in the sky. There is also a very odd adjacency processing effect round the statue, artificially lightening the sky round the dark contour. This is similar to a Smart Sharpen wide radius contrast mask in Photoshop, or the Clarity control, but it's happening inside the camera. Please view the full size, because at Large and other sizes, the clouds behind the legs of the horse make a very strange effect.

The shot is, of course, taken using Tungsten preset which turns a grey-blue evening sky into something much stronger in colour and tones down the sodium lamps of the hotel. Wellington's statue and the Balmoral Hotel, Edinburgh.