[PeterT]

There is logic in the Kobo driver to upload covers to the Touch... I will admit though I'm not quite sure how it works!

Let me experiment and see if anything happens for me.

Hmmm...

Well; I tried two books; both contain front covers which are within the books. In calibre both also contain a cover.jpg image in their respective directories. I edited one of the cover.jpg before the upload. On the Kobo the one book with an edited cover.jpg, this is the image displayed for all thumbnails along with the image displayed as the first page in the eBook.

When a book is uploaded a second time, the driver is able to determine the existing "id" for the book on the Kobo and can replace the existing cover images with new ones.