Wheatley

 was a member of the British Secret Service who thought the Tenth Doctor was an enemy agent. He interrogated the Doctor. He didn't want Hetty Warner to preserve the timelines. He wanted the House he left the Doctor in to be bombed. He had called Kahn Tareen to discover the cause of the hound. He was using the Dog to try and control Churchill's moods. (AUDIO: Hounded)