A peasant from the Middle Ages was briefly sent to London in the 1970s via a time eddy at the same time that dinosaurs were rampaging through the city. He encountered the Third Doctor and Sarah Jane Smith, thinking the Doctor was a wizard.
The peasant carried a knife to defend himself. He claimed that a witch had cast a spell on him, and was going to tell the priest so he could have her burned at the stake. He explained that his king was Richard, who was on a crusade in the Holy Land, and John ruled England now. The peasant asked the Doctor to take the curse off him, but when the Time Lord tried to explain that he wasn't really a wizard and couldn't do that, the peasant drew his knife and threatened to kill him. He lunged at the Doctor just before being taken back to the past by the time eddy.