A possibility, she was in the infirmary in a workhouse.
this link is about Ecclesall Bierlow workhouse.
Not sure about this workhouse, was there a separate Ecclesall Workhouse? If not, I've been in it, as it became the City General Hospital, Now the Northern General, bu my parents knew it as 'the Workhouse.'
This probably a daft question, did you try the next page in the census?
I think I know where you're coming from, and first I should apologize for not stating the full details as Peter says in his introductory lesson. I'll try and attach the image, and if you want to look at the entire page, it's
HO 107/1333/4 Folio 16, page 25.
As you can see, the father and three children (Mary here is my great-great-grandmother and both she and her mother are Mary Ann.
Have you found her siblings in 1841 and looked to see if she was there?
Was she with her husband in the 1851 census?
I wish I knew for certain who her siblings were. She is on every subsequent census, with John until he died. In 1861 they had a visitor, Elizabeth BAGSHAW 41 whom I investigated, and whose mother was Hannah ROBINSON, much older than Mary Ann senior, and I've worked on the assumption that Hannah and Mary Ann were sisters, or half sisters, in which case Elizabeth would be Mary Ann senior's niece and Mary Ann junior's first cousin. I found a marriage between John TURNER and Mary Ann ROBINSON on 22 June 1825 at the Sheffield Parish Church, nothing in the marriage record to tie them to my John and Mary Ann (and there's another John and Mary Ann marriage in this church in the same year, to Mary Ann NAYLOR: both marked, and amongst other things, I've assumed that John, as a saw manufacturer, could read and write. I can't prove that either.) And I'm sorry to say that there were no other children born after Alfred here or I would have been able to find her maiden surname for sure.
There's another twist: Mary the daughter was baptized, and appears at least on my great-grandmother's birth record as "Mary Ann Tyzack TURNER/BLOOMER". Why did they give her the surname Tyzack as a forename? I'd have liked to have found a marriage between John TURNER and Mary Ann TYZACK but there doesn't appear to be one. I think there was a Mary TYZACK about that age in Sheffield or environs. The only possibility I haven't followed up was they went off somewhere outside England & Wales to get married. I have tried Scotland, the obvious choice and noting there at least not on the Church of Scotland.
Now to fill in other details gleaned from the census: she was born in Sheffield (all three censuses) and was 47 in 1851, 58 in 1861 and 67 in 1871 wich suggests she was born in 1803 or 4. Mary Ann the daughter of John and Mary ROBINSON was born on 28 June 1803 which fits (almost) perfectly. One avenue I haven't tried is to check out her brother, it she
was Mary Ann ROBINSON, then she had a brother Ebenezer and could have been there, but actually I do have his 1841 census and there is no Mary there, not even his wife, also Mary Ann.
Apart from trying Mary TURNERs dwelling in Sheffield on census night, here were 35 Mary TURNERs born in 1803 +/- 1 and 240 who followed the instructions and put 35 as their age (as if born in 1806) and it would take me a year to get through all of those and would I know if I'd found her?? If they're living with a male TURNER of about the same age it's a reasonable assumption she's his wife as were all those on the Sheffield & Ecclesall census. That might rule out 80% or 90% of them which still leaves 27 or more possibilities, and you can't even rule out those who say tey were born in that county, eg Middlesex, where they were that night if the informant was careless or the enumerator simply copied the Y down the page, as happened with my Elizabeth ROBINSON/FORD who appears on the 1891 census for Sheffield as born in Sheffield when she was actually born in Weedon Bec.
Final box: the workhouse or the infirmary, if it was in the registration district of Ecclesall Bierlow or Sheffield she should still come up in my search, unless they didn't know her surname (highly unlikely, I'd have thought) or got it wrong.
Hopefully I've ticked all the boxes, if now you or anyone has any ideas, they'll be most welcome.