John, I've just realised that your solution puts all images into thumbnails. Is there some way of selecting which ones you want as a thumbnail or is it all or nothing?
I have an image that I have put links on, so want full size but when I publish, it automatically turns it into a thumbnail and then the links don't work. So I don't want this as a thumbnail but there are other images I do.
If I remove thumbnails and publish, the links on the graphic are set as an Auto-sized popup - show as expected in the preview but don't publish as a pop-up. Is this because I'm trying to publish as HTML5?