Your right Cas, the bane of genealogy is how crap the census records are

The ages ARE out but the census is in the right place and the 5 year gap between Henry and Emma works too, Withington isn't a big conurbation, i was born in the same hospital some of my relatives died in, so the chances of there being a similar family around there is slim at best.
Henry married Emma in 1879 when he was 26, he's down on the marriage certificate as an excavator, which is probably a posh labourer, its a fair stretch from Norfolk to Manchester but there would have been plenty of that type of work around that time, not so his father Henry who's occupation is listed as a drover, not many sheep or cows in Manchester then

so the search continues for the link i think.