David I did not say that the Act of Union was in no way consequential upon the Union of Crowns in 1603. I would not say that as it obviously paved the way for it - though it was not in itself a full blown certainty. However that is not what you originally said or at least it is not what I read from your statement. Your exact quote was

"The United Kingdom of England and Scotland dates from 1603 despite the various hiccups"

I simply repeated there was no "United Kingdom of England and Scotland" in 1603. There were two seperate kingdoms who shared a monarch and the two kingdoms went on to become a United Kingdom a century later. I read it as you saying that the United Kingdom was in fact created in 1603 rather than that being a defining factor in its creation a century later. If I've misunderstood what you were saying then of course I apologise.