From what I gathered from my textbook, the Indian subcontinent's people couldn't protest against colonialism if the English didn't educate them. They general mass began to protest after they got educated about the fact that what the English were doing to them was very wrong.
Hi can you clarify your question. Slavery was illegal in the British Empire from 1833, before the end of the 19th century. Do you mean protest against colonial rule rather than against Slavery?