I was going to bid on this but totally forgot it was ending, glad it went to someone on here.
Since this thread was posted and since my site went live I have been trying my best to make some sense of these QC stickers. I have seen quite a few now on Trilogo cards and also some on late Palitoy ROTJ cards. There are even circular QC stickers too (same black with white text).
The majority of these seem to turn up from Germany and England, I tried researching store names in both countries a while back just in case QC actually stood for something else - no joy on that front and as this thread proves, they are unlike any other Palitoy QC stickers. It may always be a mystery until there is some concrete evidence to show these really do have some importance..
All that said..it didn't stop me wanting to pick it up though! Just not for a premium