When Charlie first became a warrant officer for the Vault in 2011, he was given a tour by Captain Ruth Matheson, and in the Vault they came across four objects: An army jacket, a painting, crystal and a wax cylinder, which bore a significance. Each was used in one of the Doctor's many adventures. (AUDIO: Tales from the Vault) Sato and Matheson were later tasked with guarding the Master. This task was unsuccessful, as the Master managed to trick the duo and escaped in his TARDIS. (AUDIO: Mastermind)