Most DVD players in the UK can play NTSC DVDs by converting the signal into Pseudo PAL by changing the colour signal
FWIW, all Region 2 DVD players are required by the official DVD spec to handle NTSC in addition to PAL, because Japan (which uses NTSC) is part of Region 2. Not many European-market DVD players actually bother outputting PAL60 (aka "pseudo-PAL") because 99.9% of all European-market TVs are multistandard, meaning that they will happily display PAL, NTSC and SECAM natively without any need for format conversion.
Region 1 (American) players are only required to handle NTSC, so many (most?) of them just won't play a PAL disc at all even if the player is set to be region-free.
A lot of DVD players should be able to output NTSC from a PAL DVD by duplicating frames to get 29.97 fps...
AFAIK only a relatively small number of DVD players on the American market will do that because there isn't a huge amount of demand from consumers for for PAL-to-NTSC DVD conversion. They're out there, though, it's just a matter of tracking one down.
The picture quality is often a bit grotty, though. Good-quality standards conversion is quite complex (and hence expensive) and the converters in domestic decks are usually as cheap as can be gotten away with. If you don't have a PAL-compatible TV and you're in NTSC-land, the best way to view a PAL DVD is on your computer monitor.