We are home from hospital.
It is interesting how my op sparked off such a discussion!
I think the nurse at the surgery should probably have sent us to hospital, not so much because of his sats being at the level they were, but because of ds's history. tbh we saw a dr on Fri, who listened to ds's chest and did his sats - he said his chest was clear, and his sats were ok at 93. The next morning a chest x-ray showed that infection in both lungs, and a very thick white patch on his lung. And he needed oxygen, and IV antibiotics ( because he had had a course of amoxicillin, which hadn't worked, and he has swallowing/aspirating issues - something that I had mentioned to the nurse).
Usually with ds i have an instinct for when he needs to go in, but for some reason the nurse made me unsure of my instincts, hence my original post. We are well known at the surgery, and usually see the same nurse or dr, who know ds very well, and know what to look out for and always go along the lines, of if in doubt, call children's ward and get in, because he can go down very quickly.
My only gripe with the nurse (and the dr the next day) is that this is probably what she should have done, which would have saved us a night of sitting up listening to ds's breathing get steadily worse, and a 4 hour wait in A+E to get up to the children's ward.