Fair enough. That being the case then, is there anything that will still cause it to hit the US site? If I have anything filled in or similar? For example I am searching for Inversions, by Iain M. Banks. This is the US cover:
http://tinyurl.com/bodl57n which is what Calibre is telling me it has found on 'Amazon.com' and Google even though I have the Amazon metadata plugin set to UK and have tried restarting Calibre. Conversely, this is the UK version of the cover:
http://tinyurl.com/bvqmby2
I note that the metadata plugin doesn't list cover data as one of the things it obtains. I've had a look through the available Calibre plugins to see if there was one to get covers that I could configure for Amazon UK, but I couldn't find anything.