Helen A. was the feared ruler of Terra Alpha, the first of many Earth colonies.
Helen A. insisted that everyone should be happy, and made it a crime to be unhappy. With the Happiness Patrol she was ruthless in tracking down any "Killjoys" and punishing them - usually execution.
During a census by the Galactic Central Bureau she boasted that since the last census she had managed to control the population by 17% - although she did find her own methods more productive that the Bureau's recommendations.
Helen A's only real love was for her pet - Fifi. When Fifi was injured she nursed it back to health, and when the Doctor caused Fifi to be killed this was the only thing that really upset her, leading to finally understand why people felt unhappy, and that she could not force people to be happy.