Here are the Kilbourne family 10 years earlier.  You will see they also had a son Henry three years older than Sarah

 

Living at 4 Court B Northgate, St. Margaret, Leicester

George Kilbourne  46  Shoemaker  born St. Nicholas, Leicester c1845
Jemima 44   Wool Spinner  born St. Mary, Leicester  c1847
Children:
Henry 13  born St. Nicholas, Leicester  c1878
Sarah A.  10  born St. Nicholas  c1881
John 9  born St. Nicholas  c1882
Priscilla  7   born St. Nicholas c1884
Beatrice  1  born St. Margaret, Leicester c1890

 

 

This is Sarah's birth record.

 

Births Mar 1880 
 
KILBOURNE  Sarah Ann    Leicester  7a 277