I have solved this problem. It appears that the way I worded the problem was misleading. What I wanted to do was return to the thumbs view from the photos view
I didn't want to use the supplied buttons but my own "button". What I did was replace the "Close" button graphic with a new button graphic "thumbnails".
I presume there is another way but don't know enough javaScript to modify the code. Since posting I got back to reading My Learn Javascript in 24 hours book. I have completed Hour 8 so far :)