Okay well here is the path to thumbnail http://www.english-mistress-sky.com/...bs/rosie-1.jpg
Only one thing can come to mind here. If you view that thumbnail via FTP what are the permissions on the file?
They should be at minimum 664 to be viewable. I do seem to remember one host like hostway or something that throws the files to like 400
This is something they would need to fix as any files being created on the server are being set to non web viewable.