Thank you everybody for your sympathies.
Ivan the vet is performing a PM this morning in the hope that we might learn what took him and in turn help others in the future by us learning a bit more about rabbits.
I left him with Harriet over night and he has already gone to the bridge. The frail body and lovely face was not that of my Noah, it was just a shell.
He had never been right since we took him in, and had recently been treated for gut and dental issues, but this was a massive shock. As so often is said - he was perfectly normal earlier in the afternoon. Eating and coming up to the wendy house door to see what was what.
I feel like he had a stroke. His heart was beating really fast when I found him, he was floppy and had been drooling from one side of his face. He appeared to have had a seizure while I was holding him, he had already wriggled when I picked him up, but maybe he was just in such pain he was leaving us already.
I hope to know the reason he has been taken from us too soon by Ivan having a look at him more closely.
What to do with Harriet now I've no idea. She is missing him already and is very quiet. So wrong for her to be on her own in this weather. I can't see her working with any of our pairs as she is a grumpy bus, but I guess we will have to try.