Your first paragraph has already answered the question, English( not the outdated old English) is native to England.<quoted text>
Because they are from England.
It has nothing to do with the language they speak.
Guess what you call a person who can't speak English but who was born in England and who uses British Sign Language?
You call them "English".
The people who are either from India, Burma, Parkistan, Africa, etc, are known as immigrants or generally British immigrants.