Conversation so far:
What political topics was Charles Bradlaugh interested in?
Bradlaugh was an advocate of trade unionism, republicanism, and universal suffrage, and he opposed socialism.
Why did Charles Bradlaugh become an activist?
Bradlaugh returned to London in 1853. By this time he was a convinced freethinker. He gradually attained prominence in a number of liberal or radical political groups or societies.

Question: What years was he writing about his ideas?
Self-contained rewrite: What years was Charles Bradlaugh writing about his freethinking ideas?