Update #2
Well, I never thought I'd be so pleased to see & smell cat poo & wee!!!
Its taken 24hours but he's just gone through the motions, somewhat messy given his state, but at least we know his bits & bobs are working and he can do his business.
Clearly, had this not been the case, well, I'm sure you can all guess what we were dreading would have come tomorrow.
The emergency vet last night stressed that this was the most crucial aspect of measuring his prognosis, bodily functions = a very very good chance of a full recovery.
Thought I'd let you all know, again, thanks for the comments & support.
Our relief is incredible although I imagine, Archies relief is somewhat greater!