Helen A

Helen A was the ruler of the human colony on Terra Alpha. Her law was enforced by the Happiness Patrol. She was overthrown by the Doctor. Her consort was Joseph C an she had a pet Stigorax, called Fifi. (DW: The Happiness Patrol)

Behind the scenes
Patricia Routledge was originally offered the part of Helen A, but she declined. On an unrelated note, fans generally believe that Helen A served as an allegorical representation of British Prime Minister Margaret Thatcher.