Richard: On closer examination your 'GB Counties' seems a bit light! It lists only 30 counties (all in England) as against my rough estimate of about 125.http://dl.dropbox.com/u/4019461/UK%20Counties.txt
Even in England there about 64 counties.
There are of course all sorts of complex definitions about counties, boroughs, districts, etc, and I for one don't understand all the fine distinctions. But those I've listed after editing from various sources are IMO generally regarded as 'Counties' to most of us here in the UK. It's an MMO or GPX of those that I'm seeking.
Terry, East Grinstead, UK