RETRACTED - When I discover a post to be incorrect, I'll post a statement at the beginning retracting it. The information is 'true', but I've connected people incorrectly and they are unrelated.
In this case, it transpires there were two families in London named William and Charlotte ROBERTS, both of whom had family members come to Australia. I've italicized information that DOES relate to my Helen ROBERTS and her parents. The information not italicized relates to a different family. In hindsight, the discrepancies in the census data accounts for the fact my Helen Charlotte ROBERTS was not a child of the family discussed.
Related to my recent post on Helen Charlotte ROBERTS (http://thehistoryofmatt.blogspot.com/2009/02/helen-charlotte-roberts.html), born 1836 London, died 1918 Sydney, I have begun to look into her parents.
As mentioned, her parents William and Charlotte ROBERTS could be found in the 1851 census, along with siblings:
Willm Roberts, head, aged 44 (born abt 1807), a Commission Agent (Distiller), born Helston, Cornwal
Charlotte Roberts, wife, aged 35 (born abt 1816), born Stonehouse, Devon
W C Roberts, son, aged 9 (born abt 1842), scholar, Lambeth, Surrey
Henry Roberts, son, aged 5 (born abt 1846), scholar, St Lukes, Middlesex
Arthur Roberts, son, aged 3 (born abt 1848), Islington, Middlesex
Alfred Roberts, son, aged 1 (born abt 1850), Islington, Middlesex
Using the Familysearch IGI records reveals their marriage:
William ROBERTS to Charlotte Ann GANT
20 JAN 1834 at Saint Sidwell, Exeter, Devon, England
The census states Charlotte Ann GANT's birthplace was Stonehouse, Devon - East Stonehouse formed one of three coastal towns that now forms Plymouth. IGI records show the baptism of Charlotte Ann Gant:
CHARLOTTE ANN GANT, Christening: 28 JUN 1815
Saint Andrew Ebenezer Chapel-Wesleyan, Plymouth, Devon, England
Father: James GANT
As for William Roberts, indexes for Helston (http://freepages.genealogy.rootsweb.ancestry.com/~cricket5/hel.htm) reveal two William Roberts born in 1806:
William Roberts, baptised 8 Jun 1806, parents Tobias and Susanna ROBERTS
William Roberts, baptised 22 Jun 1806, parents Thomas and Sarah ROBERTS
More work to be done!