I think this must be the dust-jacket find of the day. It wasn't until I got it home that I looked to see and the artwork is by John Minton: quality will always out! The book itself is trailed really well in the blurb, "A novel which described with grim certainty of detail, the story of a band of people trapped in a New York underground after a monstrous catastrophe has sealed all the exits." Published by Methuen in 1955, it was a first novel: and possibly a last novel too if a short dig around on the internet is anything to go by!