From Amazon.com:

One day George Arthur Rose, hack writer and minor priest, discovers that he has been picked to be Pope. He is hardly surprised and not in the least daunted. "The previous English pontiff was Hadrian the Fourth," he declares. "The present English pontiff is Hadrian the Seventh. It pleases Us; and so, by Our own impulse, We command."Hadrian is conceived in the image of his creator, Fr. Rolfe, whose aristocratic pretensions (he called himself Baron Corvo), religious obsession, and anarchic and self-aggrandizing sensibility have made him known as one of the great English eccentrics. Fr. Rolfe endured a lifetime of indignities and disappointments. However, in the hilarious and touching pages of this, his finest novel, he triumphs.