Hugh Bainbridge was the pseudonym used by a genetically engineered vampire named Drusis, who put on a bumbling, amiable public school boy personality so that the Doctor's expectations of him would be low and he would be more impressed with him later when he did something heroic. Given that he was a vampire, he could not enter the TARDIS without being invited. He planned to drink the Doctor's blood so as to obtain his genetic material, allowing him to operate the TARDIS. However, the Doctor had prepared for this by setting the TARDIS to land on Mercury. (AUDIO: Situation Vacant)