I don't yet know how accurate the Ancestry Census transcription I've just seen is, but I've just found a Janet SINCLAIR enumerated with an occupation of "deceased daughter"!
This being part of the investigations into the newfound GRAY twigs that Bobby put me onto. I don't think she's the Janet I'm looking for however.
The family being researched is that of Ann, dtr of Donald GRAY and Janet SUTHERLAND, and sister of the Catherine GRAY who married John BAIN, married a James SINCLAIR. Bobby found her 1857 death certificate and I'm fossicking to see what else I can find.
So far the extended family includes McGREGORs, and another SINCLAIR family.