Furthermore, they were a major mercantile nation, and English traders could be found almost anywhere. English was a highly useful language to learn for this reason. All the important people were English and spoke English, so the ruling classes created a massive pressure for people to learn Englis.You have to remember that the Empire was massive, spanning from India to the Americas, and was so powerful and self absorbed that there was no need to trade in any other languages. These were pushed to the back of the pile as English fast became the language everyone needed to know.