Yes, that was what rather confused me - they were in the same place, Caldey Island (I'm afraid I'd got it as "Caldy", and wasn't sure which was correct at the time, so didn't name the place) prior to the 1861 census and after it, but I'd been unable to find them in the 1861 Wales census, and couldn't believe they'd up-and-off for a short period.
I'm afraid I'd not thought of "missing" pages - and I should have, for I've other, closer family in other areas of Wales in the same plight in 1861.
Thank you very much, Rhosgoch and of course, Crunwere, who has helped so many on these pages. I appreciate your time being spent on this. I'll just "file" Benjamin now, he's not really direct - just a very distant link by marriage.