So the glovebox now works. A determined effort of 20 minutes today did the trick - although I have been having a 5 minutes play with whole thing before going into evening work
A little loosening of accessible screws and nuts - including those by the fuse box - gave wriggle room. Then, after pushing up the door, the Left Hand latch locked - something that it hadn't been doing. We're getting somewhere. A little more wriggling, and a push or two of the release button, and the glove box opened. Contents: two pairs of gloves, the OBD code reader, and the Saab screwdriver with two blades. Nothing else.
What caused the issue in the first place? It's a mystery - could it have been the larger temperature variations we have had recently?
Rattle free, now, too - a bonus.
Thanks, everyone for your input.