Hi Pete,
I cannot help with the 1851 census but thought these may help you unravel the family at some point. Sorry did not find Abraham!
Kind Regards, Frances
CULVERHOUSE, Ann Christening
Gender: Female
Birth Date: 21 Apr 1829 Birthplace: 8472, Billington, Bedford, England
Recorded in: Bedfordshire, England
Collection: Dr. William's Library; Nonconformist Registers
Father: Thomas CULVERHOUSE
Mother: Elizebeth STEVENS
Mother's Father: Thomas STEVENS
Mother's Mother: Jane
Source: FHL Film 815932 Dates: 1828 - 1829
CULVERHOUSE, Caleb Christening
Gender: Male
Birth Date: 12 Oct 1832 Birthplace: 8474, Billington, Bedford, England
Recorded in: Bedfordshire, England
Collection: Dr. William's Library; Nonconformist Registers
Father: Thomas CULVERHOUSE
Mother: Elizebeth STEVENS
Mother's Father: Thomas STEVENS
Mother's Mother: Jane
Source: FHL Film 815932 Dates: 1829 - 1833
CULVERHOUSE, William Christening
Gender: Male
Birth Date: 12 Dec 1836 Birthplace: 8475, Leighton Buzzard, Bedford, England
Recorded in: Bedfordshire, England
Collection: Dr. William's Library; Nonconformist Registers
Father: Thomas CULVERHOUSE
Mother: Jane HOWARD
Mother's Father: James HOWARD
Source: FHL Film 815932 Dates: 1833 - 1837