OK I understand but i don't have any caching plugins on the test site and my hosting says they don't use servers side caching....I'm still stuck.
My main site (which was working fine until the latest update)is now displaying a broken message and I have a new 2013 site but this is also broken http://www.creightonscakes.co.uk/2013/.
Both these use W3 Total Cache but exclude cart (basket) and checkout pages.
Maybe I'm jinxed