Ok so I got some files I can't delete.
They happen to be MAC temporary/hidden files that the wretched things litter my Server 2003 shares with.
in this case there were 2 files
But I keep getting "Cannot rename file: Cannot read from the source file or disk"
Finally pulled out the IT support library called Google and first hit found
Excellent article, explains the issue, reasons and workround.
One minor point missing for me was to 'un-hide' the file.
For me the steps had to be:
Attrib -H "\\?\D:\My Share\jobfolder xy\subfolder\*.*"
Del "\\?\D:\My Share\jobfolder xy\subfolder\*.*"