It is the English language. The language was spoken in England for a thousand years before it was spoken anywhere else. It was created and formed entirely in England. No one but the Chinese can define how to properly speak Chinese. Imagine a Brit informing India that its language had changed, and if they continued using the form of their language they had used for millenia, they would be incorrect, or even "pompous" as someone said. The statement "the proper rules of the English language were decided in England" seems obvious to me. Please let an Englishman answer the question
What they say is what I am asking them. I'm interested to know. We should generally defer to the English on the rules of the English language, not assume that our way is right because it is common here. If you take an English exam in college, you can't make up grammar as you go along, on the grounds that it is in "common use". Grammar implies standardized rules that do not change, unless officially changed by a relevant authority. Common local dialect is distinct from a grammatical rule. There is also some distinction between American and British English, but it is their language.
Can someone who is competent to answer the question please answer the question, rather than offering criticisms of the question itself, or resorting to name calling? It is a legitimate question that pertains to the exact purpose that this website exists to serve.
You are incorrect in claiming that there is no official authority that decides grammar rules. There is, both in England and the United States. In England, there is a Standing Committee on Grammatical Reform, and there were official grammar manuals of sorts called "King's English" in 1906 and "Modern English Usage" in 1926. Most importanly, however, and pertinent to this conversation, is King Alfred's deliberate codification of English grammar in the 9th century when he set about making his people literate for the first time, which is why any of us are speaking English today.
Correction, there was a Standing Committee on Grammatical Reform. Nonetheless, governments adopt curricula for their schools, and those curricula include a standardization of English (not American) grammar. This is simply a fact, not an opinion. This is why English is one language, and not 20 different languages. It is also a fact that virtually all English grammar rules were established in England. It was English schoolmasters who taught America how to read and write our language. This is indisputable. You'd be well advised to accept that fact and move on.
A few commenters are acting unabashedly arrogantly, as if the nature of another people's language, which we're using, is something that our country can decide fpr the nation that created the language, where virtually all of its history of development occurred. As soon as the world starts speaking American instead of English, we can tell England what the proper rules of English are. Let's not forget that what motivated this question was partly the claim that English use of grammar was not only irrelevant, but improper and "pompous". That was posted on this website without a complaint.