From discussion on the radio & press it seems it was "UK" that stumped some people. They knew where it was when it was expressed as "Britain" or "United Kingdom". Someone in a letter to the press claimed that Geography isn't taught in American schools. Not true surely?
I'd have trouble placing every US state on a blank map myself, but then I failed "O" level Geography back in the Dark Ages.
RtS
(On a bad day I can't find my arse with both hands)