Charlie Sato

Charlie Sato was a Warrant Officer who worked in the Vault.

Biography
When Charlie first became a warrant officer for the Vault, 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)

After the escape of the Master, Sato was held at UNIT's private residence for compromised UNIT soldiers. Sato was later brought back into active service by Mike Yates, who needed his help to investigate what had happened to the Vault since he and Matheson left. (AUDIO: The Screaming Skull)