There is this Margaret Harrison in Newcastle in 1861. Would be a suitable bride for the marriage in Gateshead in Dec 1871.
1861 census.
40 Percy St., Newcastle,
Boarding with a Stafford family,
Henry Taylor, visitor, Married, 25, Coachman (dom serv), b. Northumberland, Alnwick,
Mary Taylor, visitor, mar, 25, b. Cumberland, Hayton,
Margaret Harrison, visitor, 11, b. Cumberland, Brampton.
RG 9/3820/18/30
Can't find her in 1871, not with the Taylors. But this would appear to be her in 1851.
1851 census.
Front Street, Brampton,
Thomas Harrison, head, 36, Grocer, b. Cumberland, Brampton,
Jane Harrison, wife, 26, b. Cumberland, Hayton,
Margaret Harrison, dau, 1, b. Cumberland, Brampton.
HO107/2427/145/25
Ancestry has Margaret aged 4, thegenealogist has her aged 6, but it looks more like 1 with a blob after it to me.
Fits with this birth - Margaret Harrison, Dec Qtr 1849, Brampton.
And this possible marriage - Thomas Harrison and Jane Elliott, Dec Qtr 1848, Brampton.
And this one - Henry Taylor and Mary Elliott, Jun qtr 1860, Brampton.
According to a few tangled public trees on Ancestry, Margaret Harrison is the niece of the Mary Taylor (formerly Elliott) in 1861 census, Newcastle, but disappears after that.
Looks a good candidate, but just speculation, you really need a birth cert to confirm your Margarets maiden name.
Alan.