Britain's best ever sellers

We take them on holiday and into the bedroom. We know them as intimately as our families. They are the bestselling British novelists. What is it that makes these authors - often ridiculed but obsessively read - so stupendously successful? Literary merit? Perhaps not. Some have sold their souls brilliantly to the media, while others simply had the knack or luck of perfect timing. And their rewards continue to amass.

Although Agatha Christie has sold more books, Joanne Kathleen Rowling is now richer by far. Jeffrey Archer has a fabulous collection of modern art to gloat over when he gets out of jail, and Barbara Cartland bought miles of pink chiffon with the income from her 651 books. JRR Tolkien, voted Britain's greatest author in numerous polls during the 1990s, managed to sell an extra 20 million copies of The Lord of the Rings after the release of the film adaptation in 2001 - six million in the United States alone. That's impressive, but still not quite in the same league as Agatha Christie, whose two billion sales include a massive French readership.

What were the forces that created the bestseller market, a product of the last century? And what were the skills and strategies that enabled these particular authors to master the form? To answer those questions we must go back to the First World War, when the age of the blockbuster was ushered in. The novels of Marie Corelli, Ethel M Dell and Nat Gould may now lie abandoned and unread on the shelves of the second-hand bookshops of Charing Cross Road, but their legacy can be found in the latest Aga saga, sex-and-shopping novel or international techno thriller.

In the first decades of the 20th century, a newly literate public was demanding fiction that was both entertaining and uplifting. It was the heyday of such long-forgotten writers as Gould, who produced thrilling tales of racetrack adventure that made him popular among soldiers in the trenches.

The war released violent passions. Disillusioned soldiers, who came back to a land that was not "fit for heroes" and who had grown used to death, demanded strong-willed heroes who met the world with a square jaw and a strong fist. Edgar Rice Burroughs's Tarzan, John Buchan's Richard Hannay and Sapper's Bulldog Drummond defined the genre.

Women, however, became the main readers of fiction, and have remained so ever since. The market was developed at the beginning of the 20th century by authors such as Marie Corelli, Ethel M Dell, EM Hull (a pig farmer's wife and author of The Sheik) and Elinor Glyn, who between them provided a diet of temperance, religiosity, domesticity and occasional eroticism. Tastes were racier by 1925, when Anita Loos's Gentlemen Prefer Blondes became the rage of the flapper generation.

In the 1930s a depressed British reading public acquired an insatiable taste for Americanised stories and movies, a fabulous Technicolor world of bootlegging and Hollywood stars. British writers turned their hand to producing their own gangster tales, starting with James Hadley Chase's 1938 novel No Orchids for Miss Blandish. The top spot on the best-sellers list during the Second World War was occupied by the tongue-in-cheek pulp thriller writer Peter Cheyney.

At the height of the Cold War, Ian Fleming applied the violence and sexuality of his arch-American rival and predecessor, Mickey Spillane, to imaginary superpower intrigues. Not to be outdone, his American contemporary Harold Robbins utilised thrill-a-minute, pulp-magazine scenarios and exotic locations: Robbins's The Carpetbaggers led a 1960s paperback revolution that numbered among its troops Jacqueline Susann, Grace Metalious and Jackie Collins. The books' gaudy covers reflected the liberated, materialistic lives of the rich and famous or the tedious, covertly sleazy world of small-town USA.

Since the 1970s, publishing has come to depend on a regular fix of best sellers, even though only one novel in 1,000 ever really takes off. Genres have changed to develop new markets, but the intention has remained constant: to find a formula for sure-fire success. In 1974, first-novelists Stephen King and James Herbert turned horror into bestselling fiction. In the following decade, Tom Clancy revived Cold War thrillers. A rush of film tie-ins and discount sales have made the past 20 years a publishing bonanza.

Authorship has increasingly led to cross-media celebrity. Even Salman Rushdie took a walk-on part in the film of Bridget Jones's Diary. Writing has become only one aspect of a busy schedule of interviews and media work. Jeffrey Archer's life and novels have blended into one long personal soap opera.