Looks like the whole of the Stewart family had moved to Newcastle by the time of the 1871 census:
Thomas Aldridge 26 chair maker b. High Wycombe, Buckinghamshire
Janett Aldridge 22
Thomas Aldridge 1 b. Newcastle
John Stewart 48 Father-in-law coach painter
Jennet Stewart 42
John Stewart 22
Robert Stewart 18
Thomas Stewart 14 b. S. Shields Durham
Charles Stewart 16
Alice Stewart 10
www.familysearch.org/ark:/61903/1:1:XYRS-3FNWilliam Stewart 7
Louisa Stewart 3 months
All the Stewarts, with the exception of baby Louisa and son Thomas, are showing as in Scotland.
Louisa's birth reg on the GRO index:
STEWART, LOUISA LIESHMAN
GRO Reference: 1871 M Quarter in NEWCASTLE UPON TYNE Volume 10B Page 97
I think Louisa died in 1877.
Monica