Hi icemuscle, just an update from my own experience concerning my earlier post here above and the importance of the "right" spelling. As I am constantly running tests, I reported above with an example from one of my blogs concerning "spain holiday".
As this blog is running a bi-lingual experiment (Spanish - English) I explained how it changes rankings on .es, .com and .co.uk
When I placed Spanish content it went up the SERPs on .es to #3 and lost rankings on .com and .co.uk
Yesterday I placed an UK spelling article on that very same blog, today I am back to first page on co.uk again for spain holiday. I am amazed about the new G-speed recognizing his kind of content changes.
Still testing but my best bet for the moment is exactly this, use UK spelling and I think you will be fine. (may be not as fine as in my example as I use a London server for this blog but it's still a .com not co.uk domain)
For sure, went directly down from 3 to 8 on .es !