Quote: "The SE, being sold as Region 1 here in the UK, I just assumed it was NTSC, but I just noticed the small print on the back cover actually states 'Region Free'."

I don't understand what you mean. An American DVD is in NTSC even if it's marked "Region Free". It just means that you can use it in other regions of the world (if your machine can read a NTSC signal). "Regions" and "video systems" are totally different things. And the same goes of course for PAL DVDs.