Looking at the various census his birth year varies between 1852 and 1859 although as already mentioned birthplace consistently Westminster!
I have found the following living in 4 St. Anns Lane, St. John the Evangelist,Westminster in 1871:
Head of household is Henry Brown 45 General Dealer born London
Lodger: Rebecca Venables 45 born Westminster
Lodger: Frances Venables 13 ditto
Lodger: Henry Venables 20 General Dealer ditto
Lodger: James Venables 17 General Dealer ditto
Both Henry Brown and Rebecca Venables are shown as unmarried!
Daughter Frances was indeed born in Westminster in 1858 registered as Frances Rebecca Venables. When she married in 1883 she gives her fathers name as Henry Venables, Commercial Traveller.
1. I cannot find a marriage between a Henry Venables and a Rebecca (who's shown as unmarried in 1871 anyway).
2. Are Henry Brown and the Henry Venables? quoted as Frances father when she married actually the same person?
I cannot find a marriage/remarriage for a Rebecca Venables nor a likely death. Nor can I find her after 1871 (in 1881 her daughter Frances is a boarder in Newington but listed under her second name Rebecca.)
In 1861 can only find Frances aged 3 living with a family in Westminster and she is shown as 'nurse child'. Cannot find the two boys anywhere.
Annette