"A friend" drove a (non-UK reg) car from Glasgow to Southampton last year, significantly exceeding the speed limit most of the way and maintaining >90mph for multiple hours, and wondered if speeding tickets would later arrive in the post. Nothing ever happened. I can only guess that speed camera tickets are only sent to UK registered vehicles? That's a pretty big loophole.

I don't drive like this in France, they will stop you and my understanding is you must pay the fine on the spot or they arrest you and tow your car.