The monk was meddling in history to change it for what he considered to be the better: lending mechanical assistance to the builders of Stonehenge; giving Leonardo da Vinci tips on aircraft design; making money by using time travel to exploit compound interest; and, when the Doctor first encountered him, attempting to prevent the Norman Conquest as part of a plan to guide England into an early age of technological prosperity. On that occasion he wore the guise of a monk in order to gain the trust of the 11th-century locals of Northumbria, hence the name by which he became known within this serial. The Doctor stranded the monk in the 11th century by stealing his TARDIS's dimensional controller, which reduced the interior dimensions of the time machine to minuscule size.