When a writer invents a character for the purposes of fiction, especially of light or fanciful fiction, he fits him out with all sorts of features meant to be effective in that setting and against that background. He may have taken, and probably has taken, a hint from a human being. But he will not hesitate to alter the human being, especially in externals, because he is not thinking of a portrait but of a picture.

In Father Brown, it was the chief feature to be featureless. The point of him was to appear pointless; and one might say that his conspicuous quality was not being conspicuous.

His commonplace exterior was meant to contrast with his unsuspected vigilance and intelligence; and that being so, of course I made his appearance shabby and shapeless, his. face round and expressionless, his manners clumsy, and so on.

At the same time, I did take some of his inner intellectual qualities from my friend, Father John O'Connor of Bedford, who has not, as a matter of fact, any of these external qualities. He is not shabby, but rather neat; he is not clumsy, but very delicate and dexterous; he not only is but looks amusing and amused. He is a sensitive and quick-witted Irishman, with the profound irony and some of the potential irritability of his race.

My Father Brown was deliberately described as a Suffolk dumpling from East Anglia. That, and the rest of his description, was a deliberate disguise for the purpose of detective fiction. But for all that, there is a very real sense in which Father O'Connor was the intellectual inspiration of these stories; and of much more important things as well.

—From The Autobiography of G.K. Chesterton