Thank you all for your really helpful replies, much appreciated. My developer did some testing and couldn't find an issue when she used the following
http://www.browserstack.com/screenshots/e875c0920cd03581b8aded1f198f32f27bca3473 . Not that this was what the original post was about but clearly it was flagged up as a problem from some of you. So, I am still confused!
I have decided to go with 4.6.6 and using a responsive template design. What are your thoughts on upgrading to Gold Plus- is there any mileage in paying the extra?