Thanks for the tip, maybe I'll find a second-hand copy somewhere. Yesterday I found a pocket titled : Hell's Cartographers. The Personal Histories of Science Fiction Writers. Alfred Bester-Damon Knight-Frederik Pohl-Robert Silverberg-Harry Harrison-Brian W. Aldiss (Edited by Brian W. Aldiss and Harry Harrison, Orbit/Futura 1975). On the back cover, it promises to give "the reader a unique insight into the art and craft of writing". That would be quite unique indeed

Ambulo, ergo sum!