Well that was gutting. The "parcel" arrived with many clear puncture wounds to the box. I hoped that what was within was suitable packaged to the extent that this would be superficial, but beyond the small spattering of bubble wrap to fill the void in the large outer box, there were two "cereal packet" thickness boxes, each containing the bare cards, no foam packaging, not even an anti-static bag.
Needless to say, one card is totalled, the PCIe edge connector and the SLI connector are both crushed/snapped/contorted beyond repair and likely traces on the inner layers are FUBAR anyway. The other card looks "ok" at a quick glance, though is clearly bent.
Fired off a message to the seller, which was ignored for over 24 hours, so opened a return case with eBay, which the seller has just responded to with "not my problem mate, take it up with Hermes".