Just had the vet round to have Grumpy put to sleep.
He'd not been getting any better and had stopped eating and the vet had a good look at him and checked him over after sedating him. He suggested some further treatment but felt that there was not much hope as he could not right himself or use his tail.
I didn't feel like subjecting him to xrays and further messing around and having spent this morning watching him in the tank I realised the time had come.
The vet gave him some more oil of cloves to further sedate him and a very large injection into the abdomen and he drifted away over the next five minutes. I don't think I could have euthinased him myself and it was worth the Â£60 for the vet's visit (he was a fish keeper himself and was very sympathetic)
One strange thing that happened when the vet had lifted him from the bucket and was administering the injection was that the other sighted goldfish in the tank went wild at this point banging on the glass and swimming around aggressively - as if he could see what was going on and knew what was happening!
The wife will help with the burial this evening and then I think I shall have a few beers.
Thank you all for you advice and support over the past few days
ps I've done three 50% water changes this week and the nitrates have come down to 100 and i'll be off to the aquarium shop this weekend for some more plants and probably a replacement for Grumpy.