Re: John Callow b1845 London. Em' to US 1869
I think I've now traced my CALLOWs back to 2 possible James's on the IGI b 1761 Dartford, Kent.
My "Lillian" CALLOW was actually Eliza Isabel, k/a "Lily"., b Dec 1872 Bermondsey, Surrey to John James CALLOW b 1847 Dartford and Nancy Isabella ROLLES b 1849 Vauxhall, Surrey.
They also had Wm. 1845, Maria Elizabeth 1849, Henrietta 1851, all in Dartford, and Elizabeth 1860 and Albert Arthur 1863, both in Bermondsey, Surrey.
It seems unlikely now that our CALLOWs are linked, as mine were in Dartford, Kent, in 1845, the name John has already been used for Eliza/ Lily's father, so it is unlikely he'd have had a living bro John, and Wm. CALLOW was b 1845, so unless they were twins, your John and Wm. are unlikely to be brothers!
Thought I'd share this with you anyway, in case you've found any Dartford connection. Can provide details of my CALLOWs between James 1761 and John James 1847 if you'd like them.