Have you been able to trace Robert on census until his death? I know it is Edmund you are after but it might give some clues - did he marry for instance? **
**yes I see he did in 1857, wife Eliza. Wonder if any family witnessed the marriage and if father is shown as deceased that kind of info

In 1861 an aunt and cousin are living with them names are
Margaret Cameron 45 and son George 12 both born Scotland.