@Andreas Koch Re: @Michael H.F. Wilkinson - @Kevin Johnston
In your case, the SUN would have to still compensate you for your photo, unless you sue for willful copyright infringement and can show that there is a pattern of abuse by the SUN.
I'm assuming that beyond the digital watermark, you also placed a copyright notice on the page where you made your photo public?
Of the cases I've seen, companies, not the SUN, have been pilfering images around the net with the mistaken idea that if you put your photo online, its theirs for the taking. I mean that they think that its free for them to reuse.
Now some sites have a base rule that if you don't mark your images with your own copyright, its being released under creative commons. Others say that anything you upload belongs to them - be-itch!, or rather they have the right to use it as they see fit.
In terms of watermarking, it still helps you.
How likely is it that the SUN would have a photo, the same photo you have that is geo tagged and watermarked?
If what you allege to be true is true, then you would have a very easy lawsuit. You produce your image with its watermark. The SUN can't.