I assume that you are asking "Were many mixed-race children conceived in times of British colonialism in India?" And the answer is yes, just as it was "yes" in the times of those several invasions of the Indian sub-continent by people of other origins (not European) at times in the past. Note that I use "British" rather than "English" since by the time of colonialism from the British Isles into India the "nation" was "Great Britain".
Actually that answer applies over most of the world. Very few populations anywhere have remained "pure" throughout their history, and that certainly applies to inhabitants of the British Isles - some of those have black ancestry from the (North African) black Roman legions which guarded Hadrian's Wall, and Viking, and Celtic, and Anglo-Saxon, etc ancestry, not to mention French and Germanic etc ancestry in more recent times.
If you have any heritage from the British Isles then mixtures of that sort are within your own body.