The Big Idea 2
back in Westminster, eloquent Whig voices such as Edmund Burke, Richard Brinsley Sheridan and Charles James Fox were using the Indian question as a stick with which to beat William Pitt's Tory government, and capitalise on public opinion, which was inclined to mistrust those merchant adventurers who had risen above themselves. It was bad enough that these colonial boys had become rich, but the Home Country hadn't benefited (yet).
They accused the East India Company of acting as an independent tyrant, and behaving in a manner unbecoming to the kind of English gentlemen Englishmen now wanted to become. (Burke may also have been influenced by the career of his improvident brother William, who had also gone to India to make his fortune, and failed.)
It is worth noting that one of Warren's other critics was William Wilberforce - the hero of the anti-slavery campaign. Wilberforce thought that Britain's burgeoning empire should impose Christian vlaues and laws upon the world - and not respect local laws, as Warren had tried to do.