I have a copy of the marriage printout which is quite basic really. It says he married Louisa Elizabeth Wilson on 14 November 1879 at the house of Rev Donald Stuart in Dunedin (so unfortunately no church affiliation there). There is no mention of any other Dryden's. Witness for the bride is Ellen Wilson (Cumberland St) and witness of the groom Archibald Miller (George St).
Again it lists him as a butcher.
The reason why I thought George and Margaret (Meikle) Dryden were his parents is I had that info that you found Althea that they arrived on the Jura with six children and tracing the census in Scotland there were 5 children listed: John, Thomas, George, Michael and William. So there was one missing child. When they arrived in NZ (according to BDM) they went on to have four more: Adam, Alfred, Baby (died young) and Archibald. I assumed that between the last census (I think in 1851) when only 5 kids were mentioned, Henry may have come along and he wouldn't be recorded.
But now with the death printout saying his father is John. The only other option was I was completely on the wrong track and it's a different family. Or George may have had John as his middle name, or the death cert may be wrong?
I just don't know and it's so frustrating!