Phelps was drawn to the anti-vaccination movement and became a leading anti-vaccinationist. He lectured throughout the United Kingdom. Phelps was elected President of the
National Anti-Vaccination League in 1887. In 1910, Phelps debated
Percy Kirkpatrick on vaccination. Phelps argued against vaccines, stating that
sanitation was the only remedy for
smallpox and other diseases. Phelps was the editor and owner of the
Citizen newspaper which published anti-vaccination material. ==Selected publications==