Who accompanied Mahatma Gandhi during the Champaran Indigo Movement?

Mahatma Gandhi’s close English compatriot during the freedom movement was :

Who saved the life of Gandhiji in Bihar during Champaran Satyagraha?

Who was the secretary of Mahatma Gandhi during Noakhali?

Who drew Gandhiji's attention to the plight of indigo peasants in Champaran?

The first Mass Movement launched by Mahatma Gandhi-