Perhaps a sort of de facto racial hierarchy would develop, with Indians somewhere in the middle, between Europeans at the top and Africans at the bottom. This is more or less how it often played out IOTL, for example South Africa during Apartheid.
I'm not sure how you would make this happen though, whether by voluntary migration or by forcefully dumping indentured laborers from Asia onto Africa. The British would have to (economically?) rationalize the idea of sending millions of non-white people to fill up other distant colonies, in far greater numbers than they intended (or wanted).