Who would have known The Beatles more intimately than anyone else?
You may want to go on Amazon.,com and research an author named Larry Kane. Larry is now retired, but was a notable Philadelphia anchorman on several news channels. He may not have been a close friend or relative of the Beatles, but he was the only journalist permitted to travel with them on their tours in the United States. He got to see sides of them that the general public did not see, and he wrote 2 or 3 books about his experiences. I haven’t had the chance to read them yet, although I did read excerpts and saw him several times on TV being interviewed about the books. Check out Amazon and the books. Maybe you will find out some information about the Beatles you hadn’t known before.
It could have been any number of people…Pete Best, Astrid Kirchherr, Klaus Voormann, Brian Epstein, their parents and siblings, their wives, George Martin, their children, Neil Aspinall, Mal Evans, Derek Taylor, Larry Kane…there isn’t any one person that knew the Beatles any better than anybody else, or, at least, not one that anybody can pick out of the throng of people that knew them well.