Thanks very much for the welcome
And for the quick and helpful reply.
That was my suspicion too, though I was hoping it wasn't the case! Very interesting to hear your suggestions for why people didn't get married.
Unfortunately I don't have them in 1851. I nearly mentioned in the main post but I was worried about making it too lengthy: as well as the marriage I'm also missing the whole family in both 1851 and 1871.
On the off chance that anyone can weigh in on those:
1851I suspect that they somehow evaded the census, as they lived at 4 Preston street in both April 1850 and at daughter Jane's birth in Dec 1851, but for the census that house appears uninhabited (HO107/1540/202 p 20). No idea if this would've been deliberate or not (do people deliberately avoid census takers?)
1871I have them in 1861 at 12, Wharf Road, South Hackney, and then a string of other addresses around Islington, Bethnal Green and Shoreditch for 1864, 1869, 1876 and 1879 (they seemed to move a fair bit). But despite several generic and address-specific searches haven't found them in 1871 either.
A further note: Francis died in Waterloo Road workhouse in 1879 but the widowed Susan is still around in 1881. She lived with two of her daughters at 2 Virginia Row, Bethnal Green. Unfortunately post 1881 I can't find any obviously compelling records for her (either alive in another census or a death/burial).
A very slippery family when it comes to official records!