William and Mary A Oman can be seen in 1841 living at Tower Hamlets, Wapping, London, England. Mary was listed as a publican.
Ann Oman 40 Publican
William Oman 40
Mary Oman 16
Elizabeth Oman 15
Maria Oman 13
William Oman 9
Ellen Oman 4
__________

They can be also seen at the 1861 census at Public House, Little Thames Street, Whitechapel, Middlesex, England. William was born in around 1801/2 in Buckinghamshire, England. He was identified as a Dock Master at the 1861 census. His wife was also born in about 1801/2 in Bermondsey, Surrey, England.
The following details appear in the 1861 census:
Name Relationship Condition Sex Age Profession Where Born
OMAN, William Head Married M 59 Dock Master Buckinghamshire
OMAN, Mary A Wie Married F 59 Bermondsey Surrey
KNIBBS, Marion Granddaughter F 14 Scholar Mile End Bermondsey Middlesex
MUNFORD, Ellen Granddaughter F 12 Scholar Aldgate Middlesex
CARR, Thomas Visitor Widower M 47 Master Mariner Lynn Norfolk
DALYLEITH, Ann Servant Unmarried F 59 Cook Limehouse Middlesex
SPACKMAN, Mary A Servant Unmarried F 18 House Servant Shalford Essex
RUSHWORTH, Maria Daughter F 35 Limehouse Middlesex

I believe that the Granddaughter given as Marion Knibbs age 14 is in fact Maria Knibbs, the daughter of Edwin George KNIBBS and his wife Elizabeth (Oman).