Wow - fast response!
Thanks guys - that will give my nieces lawyer something to get onto now we have a name and address. She could only remember that it was 'an artist' who promised payment then apparently re-registered the aircraft in his name without paying for it.
It may be too late to do anything legaly now - but then there are always 'the boys' who can visit the fly man and suggest he pays up!
Thanks again, especially for the register link - why didn't I think of that?