So, the Imago I bought on eBay is not in as good condition as the seller's description implied.
"This is a pre-owned but well taken care of Tom Bihn messenger bag. It comes with an Absolute strap. It's silver/black in color. It has a custom embroidered trident symbol sewn into cover flap as seen in photos. The bag measures approximately 14 inches across and 12 tall. It has one main compartment with two open top pockets on the inside of the main compartment. There are three zippered compartments on the outside and two open pockets. All straps, handles, zippers, buckles etc. are in good working order. In addition to the shoulder strap there is also a carry handle."
In fact the cork fabric is badly worn (cracked and peeling in places) - I have a cork OP that I bought on ebay, so I know what well-cared-for cork looks like! This bag is old enough (c.2009) that it long predates the quality issues with cork that caused it to be discontinued. Also the main buckle is broken on one side, and there are no loose pieces in the packaging to suggest it happened in transit. Apparently "good working order" means "damaged but usable" to this seller
Sorry for the rant - I've opened a case with eBay to see if I can get a partial refund - but I needed to vent my disappointment...
ETA: if anyone has any ideas on how to "rescue" damaged cork fabric so that it doesn't deteriorate further, I'd be very grateful!