At last!
I wound the yarn (80% merino/10% cashmere/10% nylon) in the summer of 2009, began a cabled sock, decided it didn't cut the mustard, unravelled it, and in March 2012 cast on the first Cauchy sock (from Sock Innovation by Cookie A.). I finished it last month, went straight on to the second one and cast off today.
I made a mistake on the top of the right foot, but a blind man running for his life wouldn't notice, so there it will stay.
If I were to make them again I'd do a ribbed cuff instead of the picot one, but otherwise they are fine, they fit well, and I'm glad to have them finished.
Edited to add: I've now blocked the socks (I gave them a good wash and eased them into shape), and the yarn has fairly bloomed.