It is the persistent belief among countless people who read fiction that it is not really fiction at all, but a thinly disguised version of reality. Characters do not arise in an author's imagination, they believe, but are modeled on the author's family, friends, relatives and enemies. When they meet an author, the first question they ask is often: "Isn't Character A really based on Person B?" All the poor author can do is shrug his shoulders and issue yet another denial.

Occasionally, though, the author must acknowledge the question's validity. Real people do find their way into novels and stories, and not as infrequently as some authors would have us believe. The literary detective with time and patience can track many fictional characters back to their roots in actuality. Often they are changed radically in the passage from life to fiction -- as James Thurber wrote, "Even those commonly supposed to be taken from real characters rarely show much similarity in the end" -- but it remains that they did begin in the real world, as people whom authors knew and found likely subjects for fictional portrayal.

There can be no question that when it comes to sleuthing in this interesting if trivial department, the all-time champion is William Amos. He is a magazine editor who lives in England's Lake District and once "jotted down the names of thirty characters and their originals"; 10 years later he had 3,000, most of which are to be found in "The Originals," a reference book that few are likely to use for reference -- who on earth could profit from such information? -- but that many will read for pleasure and amusement.

Amos has collected all this arcana, but to his credit he does not take it too seriously. He knows that writers are telling the truth when they say the relationship between original inspiration and fictional character is often extremely slight, and he writes approvingly: "Forster, Huxley, Isherwood, Mauriac, Moravia and Powell -- all have described their use of real people; and all have echoed the emphasis placed by Charlotte Bronte on reality's role in suggesting, never dictating events and characters." He also recognizes that identifying originals is something less than important, and agrees with W.H. Auden's comment that "anyone who wastes his time trying to identify Shakespeare's dark lady seems to me to be a fool."

"The Originals" is appealing not because anything in it really matters, but because it is simply fun. It is amusing to learn, for example, that A.A. Milne's Eeyore was based on a "strange, unlucky man" named Sir Owen Seaman, of whom Milne wrote that he had "not only the will to win but the determination to explain why he hadn't won. There is a story of him as a golfer, making an excuse for every bad shot until he got to the last green, when he threw down his putter and said: 'That settles it. I'll never play in knickerbockers again.' " On the other hand, amusing is not exactly the word for Ed Gein, prototype for Norman Bates in Robert Bloch's "Psycho":

"In 1957, police investigating the disappearance of a Plainfield widow acted on information that Gein's van had been seen near the woman's hardware store. At Gein's farm they found her hanging by her heels in a shed. She had been decapitated and 'dressed like a deer.' Her heart was discovered in a coffee-can on a stove. Nine death masks were found in the house, where chairs were covered with women's skins. Gein had killed two women, taking the remains of thirteen more from their graves. He died in a Wisconsin mental institution in 1984, aged seventy-seven."

A number of people have inspired more than one fictional character -- among them Lord Balfour, W. Somerset Maugham, D.H. and Frieda Lawrence, Ezra Pound, Violet Hunt and Ernest Hemingway -- but the most beguiling of these is little known outside the small world of foreign correspondents. He is Robert Hughes, a legendary Australian journalist who died two years ago; he inspired Ian Fleming to create Dikko Henderson in "You Only Live Twice" and John le Carre' to invent Bill Craw in "The Honourable Schoolboy." Of the latter Hughes said: "Craw works ten times as hard and far more effectively than I do. I must also insist that he drinks ten times as much as I, and takes far more interest in ladies than my stern Chinese wife allows me to. His grossly improper association with MI6 -- or is it SIS? -- is something of course completely beyond my ken."

So too is much that you'll find in "The Originals," because many of the characters Amos has identified are obscure people from minor books. A further complaint, from this side of the ocean, is that the book has rather too much of a British bias; had Amos known more about America, for example, he never would have claimed that Roy Hobbs, in "The Natural," is based on Babe Ruth, and he would have identified many more originals than he does in the fiction of Saul Bellow. But browsing around through all these characters is fun, whether they be famous or unknown, British or American. For literary trivia mavens, "The Originals" is a gold mine.