John Robert Stuart Pringle used several pen names. His principle pseudonym was Gerald Verner. In his early writing days he used the name Donald Stuart, under which name he wrote 44 stories for the Sexton Blake Library as well as six stories for Union Jack and three for the Thriller magazine. In addition he wrote two stage plays, 'Sexton Blake' and 'The Shadow', two films, 'The Man Outside' (1933) and 'The Shadow' (1933) under the Stuart name. He became a hugely successful thriller writer, producing more than 120 novels that were translated in 35 languages. He also used the pseudonyms Thane Leslie, Derwent Steele and Nigel Vane.