The countries settled mainly by people from the British Isles were English-speaking, in particular:
Australia, New Zealand, most of Canada, much of South Africa. (When the Thirteen Colonies were part of the Empire they also came into this category). In addition, most of the British Carribean Islands though the population of most of these islands is Negro.
In other parts of the Empire, such as India, English was used as the main language for trade, administration, politics and education.