Zip file did it: FIle Gallery Thumbnails broken, {img) tag inconsistant
Ok here's part of the puzzle. The images were upoaded as a single ziped file. The gallery un-zipped them and made thumbnails, all good, BUT it also created a whole set of broken things with the same name as the original files, only prefaced with ._
i.e. a zip containing
photo1.jpg
photo2.png
photo3.gif
winds up in the gallery as
photo1.jpg
photo2.png
photo3.gif
._photo1.jpg
._photo2.png
._photo3.gif
The last three are not images and are only 340 bytes in size.