In the 1841 census Diana Street, Westgate, St. John, Northumberland.
Head Sarah Blyth, age 35, independent born in Northumberland.
Ann Blyth, age 25, born in Northumberland.
John Blyth, age 25, independent, born in Northumberland.
Isabella Blyth, age 6, born in Northumberland.
(remember adult ages are rounded to the nearest 5 years)

In the 1851 census there is an Isabella Blyth living at 26 Gibson Street, Newcastle upon Tyne, Northumberland
Head John Blyth, unmarried, age 40, teacher (reading and writing), born Ponteland, Northumberland
Sister Sarah Blyth, unmarried, age 44, seamstress, born Ponteland
Sister Ann Blyth, unmarried, age 42, seamstress, born Ponteland
Sister Isabella Blyth, age 16, born at Ponteland Northumberland.
[Ponteland Park is less than 5 miles from Newcastle.]