Ok - this is starting to hurt my brain now...
My Post Cats are set up like this:
China (top level)
All is fine except for the posts in the Testimonials > Shanghai category won't display essential page elements correctly (category lists, top level category title etc...), simply because 'Testimonials' is alphabetically after 'Shanghai' and therefore assigns the 'Shanghai' category as the posts main category. And this goes for any sub category whose name starts with alphabetical prominence.
This occurs in my archive.php and single.php
How can I get wordpress to ignore the alphabetical hierarchy and use category ID for prominence?