Can anyone tell me what the difference is between a FW 221 and a 222? Prices vary incredibly! Apparently there are fewer of the 222s?

The 222 Featherweight has a removable base to convert it to a free-arm and you can also drop the feed-dogs. There were fewer of them produced. I understand that because of patent protection, more of them were sold in Canada than in the USA.

Explains why most of the ones for sale are in the UK!?

I have one of each (white 221, black 222) As I understand it, I think all the 222's were made in Scotland - those sold in Canada/USA were shipped there, and then had the lower voltage motor fitted at that point.

If I've got it wrong, then I apologise. I do know that mine 222 is called a 222K because of being made in Scotland, and both mine have the higher voltage motor.