OK then yes the Angles helped bring about the name England and English from Angleland and Anglish but the English language deviates from old and middle German like Frisian. Frisian is the closest foreign language to English. Everywhere in the world where English is spoken was spread by agents of the king or Queen of England. So England's English is the oldest and most correct form of the Germanic language of English. No I'm not thirteen but thirty-two tho I am dyslexic but have studied Fourier Transforms and Matrix Calculus as a student. So you may laugh at my language skills but at least I can count.
No, no, no. Modern English comes from Middle English, which comes from Old English, which comes from Proto-Germanic, not German. What you count as a foreign language or as a separate dialect is a political question, not a linguistic one. See
Scots for an example of a debated one that's either a dialect of English or another language.
As for England's English being the oldest, you could make that argument but not of Modern English English. The speakers of the
oldest variety of English have been dead for more than a millennium and speakers in England are not any closer to ancestral varieties than native speakers elsewhere. I'm not sure how you conflate oldest with most correct, but English English isn't older. It's not like a seed was planted in North America and in Oceania that grew up into some new species of English language with some minor mutations that are still understandable. Any variety of English can be traced back to PIE.
British varieties of English aren't even, generally speaking, conservative. (An often exaggerated claim is that for that, you need to go to the Ozarks or Appalachia but that's mostly lexical, not grammatical and certainly not orthographic.)
Spread by agents of the king or Queen of England? (Also, nice capitalization scheme there.) Nope. Sorry, but not everyone that departed that isle was an agent of the king. Most were not. (Subjects, you could argue until the late 18th Century, but not even that if you count Scots as just a dialect of English (the United Kingdom didn't exist until 1707 and if you count from the union of the crowns (James VI and I), that's 1603, but agents of the man himself rather than agents of the institution would be a much harder claim to support.)