Counties - US ones but based in UK
I tend to avoid using the drop down field for counties in the UK since - unlike States in the USA, or Departments in France, for example - there is no one true definition for them (is it London, Greater London, Islington, etc.).

Instead, I remove the county drop down and add another supplemental address line if required.

Although there are some forms on the web that use a drop down for counties, I suspect more than half just use a standard text field.

Flippant side note: the important thing to collect for UK addresses is the awesome UK postcode. As soon as you have that, everything else pales into insignificance :)