George of St Albans

George of St Albans was, according to the Fifth Doctor and Nyssa, the person whom legend believed slew a green dragon, became a symbol for England, and was eventually sainted. In truth, however, he was an apothecary who stole the identity of Hubert, sixth Earl of Mummerset, whom he had nursed on the battlefields of Palestine during the Crusades. On returning to England, he attempted to claim Stockbridge Castle as his hereditary home. Eventually he was discovered, and the people knew he wasn't the hereditary earl. However, when he appeared to have slain the "green dragon" — in reality an exploding Rutan ship — the people rallied around him and effectively gave him the earldom by popular acclaim. Whether that title was in fact formally conferred on him by the King of England — who actually had the power to make it "legal" — was unknown. (AUDIO: Castle of Fear (audio story))

Behind the scenes
The DWU's account of Saint George is significantly at variance with genuine history. Of the many details with which Big Finish took great liberties was the time frame of his life. The real Saint George was from the late 3rd century, whereas this character dates from centuries later. The suggestion by the author of Castle of Fear is that Saint George was actually alive during the Crusades, rather than, as is actually the case in real life, a legend based on a 3rd century life, that was brought to England from the Middle East at around the time of the Crusades.