This is a very interesting question. Although not familiar with the exact trajectory of India’s demographics over the period, I know of several things that started its population growing beyond what it would have been pre-British colonisation.
Expansive Economies and Limited Economies: Industrial capitalism is characterized by population growth, economic growth, expansion and intensification.
“Si spegne, signori, si chiude”
("Lights off, gentlemen, we are closing down”)
Recently a well-known professor of Siena University, a hydrology expert and director of FAO development projects in Africa, launched an extraordinary thesis, using instruments of cultural anthropology, in an Italian publication.
Were "Intact Aboriginal Cultures" really good "environmental custodians"? Not in North America Mate