Sydney Horler was born in Leytonstone (then still within Kent) and was educated at Redcliffe School and Colston School in Bristol. His first job was with Western Daily Press and Allied Newspapers in Bristol started in 1905. This lasted until 1911 when he left to become a special writer on the staff of Edward Hulton and Co. in Manchester. He moved to London to work on the Daily Mail and Daily Citizen, although he also worked in the propaganda Section of Air Intelligence toward the end of the World War I. After the war he became a sub-editor at the John O'London Weekly. In 1919 he had an argument with the editor and was fired, so he decided to become a full-time writer. His first novel, The Mystery of No.1, was published in 1925.