OK, now that we can see that it is in fact the
only hole, and that it is equidistant from top and forward edge, it must be the pivot hole after all. Close-ups like
are sometimes difficult to evaluate, because, for example, the curvature is cut off, so it looks like the whole right edge is curved, when, in fact, it goes straight right outside the frame.
@Pogo - open your own post using the "edit" button and you will see how to link gallery pictures to your posts -- if you post them in your user gallery, instead of the general one, then you can use the "gallery" button in the editor to directly select the image to be included, otherwise you need to click 'album' and then insert, manually, the ID number of the image.