What were the sources of economic drain from India to Britain?

According to Dadabhai Naroji, Indian wealth drained into the English coffers through the following sources:

1. Massive export of Indian farm produce: The Indian farmers diverted huge portions of land away from food crops and towards commercially important crops like cotton and tea. These were then exported to Britain to fuel the industries in the continent, as agriculture had substantially declined in post-Industrial Revolution Britain.

2. The British troops and officers deployed in India drew heavy salaries from the Indian cash reserves, and sent this money to their homes in Europe.

3. Britain produced goods were flooded into Indian markets, and being cheaper than their Indian counterparts, they generated massive profits.

4. Heavy taxes imposed on the public were also sent back to Britain and were not invested in the development or upliftment of the people.