Oh, I'd say the Palestinians considered the influx of millions of Jews into "their" homeland as provocation. After all, the authority for this was only based on, how did you put it, "a private letter written in 1917 expressing the unilateral position of the British government". Not very authoritative now, was it?
A far as the UN goes, they were respected by Israel only when they served Israel's purpose -- as in designating the 1947 boundaries of the Israeli state. That was followed by, "Thanks. You can go away now."
Again, does Israel honor the Fourth Geneva Convention or not?