Oliver Davis was one of the children that Missy was a governess for as well as his sister. He was expelled from his previous school after setting the library alight. He didn't like Missy initially but eventually came to like her. When they visited Crystal Palace, Oliver and Lucy hid inside a dinosaur. He helped Missy when she was accosted by a park keeper and was curious about the ruby. He liked helping Missy and managed to sneak her onto the underground. (AUDIO: A Spoonful of Mayhem)
Two years later, he was placed in a boarding school in Scotland. Missy told him that he was to stay over the Christmas break and to send a letter back home. This brought his sister Lucy to the school bringing Strax with her. He started to look for more evidence of Missy's plans. (AUDIO: Brimstone and Terror)