Pollitt

 was an SIS agent who was active in Berlin in 1933. He was the owner of a nightclub. Pollitt met Susan, and tried to take her into his confidence in order to uncover how the First Doctor had newly-minted Roman gold. He later interrogated Susan and the Doctor, but was tricked by Susan when she threw several chemicals onto the floor, declaring that the hydrogen gas would set the place alight if he fired his gun. (AUDIO: The Alchemists)