Reciprocally, the British Empire adopted aspects of cultures they colonized, including taking (stealing) artifacts (some of which still reside in European museums – more tourists, more people learning English) and certainly the vocabulary of the English language has been augmented by colonial expansion. So, British imperialism didn’t just enhance the spread of the language, it also made it the international language since the people who spoke it were everywhere. It is often cited that at the height of the British Empire, the sun never set, meaning that they had so many colonies all over the world that there was never a point during the 24-hour day when the sun was not shining on some portion of the Empire and thus on some part of the Earth, people were speaking English – all the time.
Despite the fact that the language became universal largely as a result of colonialization and exploitation, the language also spread and has flourished because of its versatility. Like any language, English has rules, but seemingly more than its fair share of ‘exceptions to the rule.’ English speakers are not afraid to adopt words and concepts from any other language and it must continue to do this, even in postcolonial times, to remain the international language that it is. This happens automatically. Words are spoken, and if used enough, they make it into the dictionary.
Early in the progression of the English language, it was already becoming an amalgam. It was mostly Germanic when William the Conqueror invaded in 1066, a Norseman/French, and forever changed English with the inclusion of French throughout England at that time. As liberating as it is to have an international language (if you can call English international without offending the international community), English is like a giant company that buys parts of smaller companies and sells them itself. Other languages do this as well, but not to the same extent. Definitely credit the expansion of the British empire for that. And since the empire expansion was also about mining resources and establishing trade, English ingratiated itself as the international language of business.
The biggest effect by far is that English became a truly universal language. The expansion of the British Empire meant that English became the official language of such diverse areas as Canada, the present United States, South Africa, Australia, and points between. The old expression was "the sun never sets on the British flag." By colonizing, the British spread their culture, and English became the most widely spoken language in the world. Airline pilots (with the possible exception of Russia and China) always communicate using English. This would not have been possible had it not been the expansion of the British Empire.