Mary Bick
born April 1806–April 1807
  in Westbury-on-Severn, Gloucestershire
died 1881–1891

Surname from son Alfred Henry's birth certificate.

1807: the baptism of 'Mary Harper, base born Daughter of Sarah Bick' is recorded on 1 November in Westbury-on-Severn. The surrounding records only show the child's forename(s), so it is not clear whether Harper here is supposed to be a middle name, or an attempt at giving the child her father's surname.

1841 census: living with children in Westbury-on-Severn. Age is 30–34 and she is said to be born in the county.

1851 census: living with husband and children at Hawkins Pill, Newnham. Age is 47 and place of birth is Westbury-on-Severn.

1861 census: living with husband, children, and grandson (William Knight) at Hawkins Pill, Newnham. Age is 53 and place of birth is Westbury-on-Severn.

1871 census: living with husband and grandson (William O. Turk) at Hawkins Pill, Newnham. Age is 64 and place of birth is Westbury-on-Severn.

1881 census: living with husband and grandson (William O. Turk) at Hawkins Pill, Newnham. Age is 74 and place of birth is Westbury-on-Severn.

Can't find her in 1891 census—presumably dead by then.