I've seperated him from Desmond now and put lots of lovely tempting food out for him to see if he eats it. Don't really want to stress him out with unnecessary vets trip if I can help him here.
He has just had a little drink from his bowl. Is that a good sign?
I think he may need the vet though, I really do. A drink is good but unless he's eating as normal he must see the vet urgently. I would not separate him from his bonded partner - that would cause unnecessary stress.