The brilliant artist is James Nunn, who also did Hideous Creatures - you can see more of his work here.
I notice new things every time I look at this cover. It's beautiful and weird and kind of melancholy. To me it brings to mind art deco posters - like the Mucha ones below which I hung above my desk when I first started writing this book, becoming something of a reference point for certain sections of the story.
So now begins the two-month countdown to release day, i.e, the day when I hide my head under a blanket and switch of my phone and slightly wish I'd never written anything.