First British edition, first printing. Signed by Olaf Stapledon on the title page. [i-iv] v-ix [x] xi-xii 1-339 [340: printer's imprint]. Bound in publisher's blue cloth lettered in purple; lacking dust jacket. Very Good+ with toning to spine, light wear to extremities. Foxing to all edges; contents slightly musty. The author's fourth novel of influential modern sci-fi, uncommon signed.