Knowing how hard it was to find info on this family, that's superb detective work. I posted this request a few months ago now and did since find both of those references, but truly appreciate you looking too.
Just to let you know, that I figured out that Frank was illegitimate, as was his brother who was named Alfred with Delmar and Van Toll attached. He died within the same quarter as his birth.
Upon ordering the naturalisation papers (which were fascinating, but didn't lead anywhere) Henry claimed to have had Dutch parents, had only lived in Holland for 6 weeks (to his knowledge), only knew English as a language, had no known living relatives at the time of application, except one aunt that also lived in England - but I know nothing of her whereabouts or name or which which side she born on...etc etc, just 'aunt'.
Still haven't found the happy couple in 1851, but they weren't in Holland then!
Thanks Jorose, I'm sure they'll turn up some day. It's only the blood line to the wife that I'm after now, although I'm definitely still curious to know about the man whose name was passed through my family for 3 generations. Unfortunately, it died out with the birth of girls in the 1920's.
Kind regards, Kirsty