I'm thinking a warm gray...it would accent the mirror and go beautifully with the color of the fire surround and the gray floor. You could do the chimney breast (the bumped out wall) in a slightly darker shade that the other walls. As noted above, look at the Affinity Colors from Ben Moore as your inspiration, then you can look at other manufacturers. Also, not that you asked, but replace the "feathers" on the mantel with something else...they're too close to the look of the mirror and almost look as though they have fallen off...use them elsewhere in the room, grouped together.

what are the best lighting tracks and bulbs for long narrow hallway with a high ceiling. I live in UK so general advice would be helpful. Thanks

Newly built kitchen with natural light and velux window at dinning area . Kitchen area has a peninsula and no natural light

How about painting out all your wood and windows a charcoal grey, not gloss. Then maybe a light blueish grey paint for over the render. I think it will look v smart