Odd! I worked back from Susannah Jones living at Broad St, Wallbrook in 1879 (actually in the 1881 census), and found her married to Joseph, with the oldest child being 10.
I found them in the 1871 census with the oldest child being just 4 months old so I presume they wouldn't have been married too long before that (other children may have died of course).
The 1868 freeBMD listing is the only one I can see in the west midlands that would fit with this time scale. Maybe it's not the right one? Both Joseph and Susannah were born around 1843 so may have been married previously --
(though Joseph is unmarried and with his parents in the 1861 census - I know it's him as his father is with him in the 1891 census, and the childrens' names match).
arrggh! why is nothing ever simple?