Ah, I see it now - thanks for the correction.
Thus the laws are potentially in conflict when it comes to the use of a non-UK-issued JAA PPL to fly an N-reg in the UK. If I'm a UK citizen (er, sorry, subject) with no intention of getting an FAA licence, why should I care if my use of an aeroplane that happens to have an 'N' painted on the side in compliance with UK law happens to violate the law of a foreign state?
Because Aircraft have the "nationality" of the state of registry and you should obey their rules as well as ours... a moot point in the case of N regs as both UK and US law allow you to fly in the UK on a UK issued PPL. And probably moot anyway as nobody checks.