Craven..I have spent a long time on this since i saw the enquiry on your own thread.............There are a number of problems, and possibly one or two clues...........Margaret Sarah Meredith appears nowhere after her baptism at All saints derby......You would expect her to be on the 1841 census..she is not....nor is she on any other Census.
James Meredith certainly did not come from Derbyshire..have checked all the marriages pre 1830 in the County.
Margaret Sarah..must have been known as either Margaret or Sarah..but that doesn't find her either..have you got any later history for her??? a marriage or a death or even siblings.......
So how do we find James Meredith?

with difficulty............so I searched every possible records for a James Meredith born say 1810-1814.....married to a Sarah Ann........several possibles..and then married simply to a Sarah..more possibles.........but only possibles.
Meredith is a Welsh name..we have a James and Sarah Ann from Staffs/Welsh border area..........and several in Wales...........you see its too big an area.........
I think he might have been in the ARMY......don't ask me why but there is a sort of thread from Stepney in London..Bethnal Green and a couple of Army establishments........and there is a very real possibility that Margaret Sarah was the last of the children..the others being born earlier in Stepney...........this is all speculation.....and the baptism in Derby was a one off flying visit.perhaps because he was only in the area
on Army duty?

??
Is it possible tha Margaret S
arah died before 1841?

there is no sign at all of a Margaret or a Sarah born Derby 1830 anywhere that me very long tentacles can reach..........
As for the All Saints Derby entry......its too early for anything other than parents names..........
Do you have any other information?

?
Derek.