lewis1 - 3:45 pm on May 8, 2013 (gmt 0)
@sheffnet, I have seen this issue of not ranking in Google.co.uk but ranking in Google.com many times....and there is an unbelievably easy fix :)
This works every time....
Remove ALL keywords from the home page title tag. Replace with anything as long as there are no domain keywords in the title tag.
Go into GWT and instruct Google to recrawl the page ASAP.
As soon as it gets recrawled and indexed it should be ranking well again without the keywords in the title tag.
This has worked every time for me. Give it a try and let me know.