As literacy and leisure time expanded after 1900, reading became a popular pastime. New additions to adult fiction doubled during the 1920s, reaching 2800 new books a year by 1935. Libraries tripled their stock, and saw heavy demand for new fiction.
A dramatic innovation was the inexpensive paperback, pioneered by Allen Lane (1902–70) at Penguin Books in 1935. The first titles included novels by Ernest Hemingway and Agatha Christie. They were sold cheap (usually sixpence) in a wide variety of inexpensive stores such as Woolworth's. Penguin aimed at an educated middle class "middlebrow" audience. It avoided the downscale image of American paperbacks. The line signaled cultural self-improvement and political education. The more polemical Penguin Specials, typically with a leftist orientation for Labour readers, were widely distributed during World War II. However the war years caused a shortage of staff for publishers and book stores, and a severe shortage of rationed paper, worsened by the air raid on Paternoster Square in 1940 that burned 5 million books in warehouses.
Romantic fiction was especially popular, with Mills and Boon the leading publisher. Romantic encounters were embodied in a principle of sexual purity that demonstrated not only social conservatism, but also how heroines could control their personal autonomy.
Adventure magazines became quite popular, especially those published by DC Thomson; the publisher sent observers around the country to talk to boys and learn what they wanted to read about. The story line in magazines and cinema that most appealed to boys was the glamorous heroism of British soldiers fighting wars that were exciting and just.