OK, so now I have a new method of going about things and I'm so nearly there, but can't get it working. I'm using this piece of Javascript modified from a d'bug post
http://itiz.in/12u7 If I remove the "medium" from the mix, I get an alert box with all three image URLs, no spaces. If I add "medium" (which is the size I need) I get no response, and Safari's Web Inspector says "TypeError: Result of expression 'attribute["Image"]' [undefined] is not an object.". I just need to grab that medium image URL, but it's proving very hard!