I'm a linguist doing research on the emergence of new dialects of English spoken in former colonies, especially India. These new dialects have two major influences: (1) Interference from the mother tongues of the learners (colonised), and (2) input from the dialects spoken by the colonisers.
There is good evidence on (1) but (2) is harder to establish, at least for me. (1) is a linguistics topic I am well acquainted with, but (2) is mainly a history question. Perhaps I'm ignorant of important work in this area, but textbooks on Indian colonial history do not deal with the question in as much detail as I need.
- Which regions of the United Kingdom did (a) employees of the East India Company, (b) colonial officers of the Raj, (c) military personnel during the Raj, and (d) missionaries come from?
- What was their educational background? (university graduates, grammar school, only basic school education?)
- How many people belonging to each of these groups came from the UK to India at what time?
The Indians that learned English during the colonial period were mainly those that worked for the East India Company/the Raj. Some of them went to schools founded for that purpose, others (partly or mainly) acquired English informally. The level of education of colonial personnel is important because university graduates were likely to speak Received Pronunciation or an approximation of it, but less educated speakers were more likely to speak the dialect of their region of origin (say, Scotland or Yorkshire). Missionaries are particularly interesting because they founded many schools for Indians (many, but not all of which taught (in) English).