Came today. JYB doesn't appear in any list I've got access to, but seems to be still alive JYB : Horbinor - grossiste - bijoux - JYB. Perhaps not so obscure after all.
Nice octagonal case with some plating wear.
Cupillard 233 inside - as usual -
The crystal seems to be flat mineral glass - somewhat scratched, but wearable. The back has 'quartz' on it so I'm guessing that its not original.
Working OK so far. Nobody else wanted it so I got it for 99p.