A young boy discovers an erudite, mushroom-loving dragon living in the Downs above his home. The two become friends, but soon afterwards the dragon is discovered by the townsfolk, who send for St George to rid them of it. St George, by this time, is quite elderly and has little interest in slaying dragons, though he resolves to do it as it is his duty.
(Summary from Wikipedia)
The text for this book may be found at www.gutenberg.com.