topr8 - 9:52 pm on Apr 27, 2013 (gmt 0)
personally speaking as a british subject, whatever the niceties might be i use GB and UK synonymously and everyone i know does the same.
although back to the original question, as Samizdata said
>>But for a "country select field", United Kingdom is the correct usage.
and this is what i personally would expect to see, and whether it is technically correct or not, it is conventionally correct.
... as an aside regarding the differences - many years ago i bought a car with NI plates (eg it had originally been registed in NI) and legally i was supposed to re-register the car with the DVLA and be issued with a new number plate, this would not have been the case if the car had originally been registered in either scotland or wales.