I was worried about Mystère, who hadn't eaten for two days and spent the night in a comatose state on the bed. But he looked just well enough this morning for us to opt for Spanish class rather than a second visit to the vet; we decided we'd review the situation later. The class was good: more conversation, less grammar than last week.
We stopped off in a supermarket on the way home to buy some frozen white fish for him; when we arrived he was feeling lively and clamouring to go out, so I poached a small portion of fish and he ate about a tablespoon. Progress!
Then we went off to the beach for a couple of hours, but it clouded over so we returned earlier than intended to a newly complaining cat. He's eaten a little more fish, we've had pasta and wine, and now it's a quiet evening at home for all of us to recover from the stress.