I don't know if this is a possible Sarah Mather in the 1851 census. Living here Longhurst Lane, Mellor, Hayfield, Derbyshire with her grandmother.
This is the same address for the 1861 census I found of Ann Spilsbury.
Registration District Hayfield
Sub District Hayfield
Enumeration District 6D
Schedule 75
Series HO107
Piece number 2153
Folio 289
Page 22